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How to Wire Buildings: 


A MANUAL 

OF THE ART OF INTERIOR WIRING. 


AUGUSTUS NOLL, E. ED., 

| % 

Member A m. Inst, of Elec. Engineers. 


WITH MANY ILLUSTRATIONS. 

FOURTH EDITION. 


New York 


C. C. Shelley, Publisher, 
66 Park Place. 


1895- 






T\\321\ 

M 

\%9 5 


Copyright, 1893 : 
Charles C. Shelley, 
New York. 


J*y Transfer 


WAY 11 1«12 


’ Ay ^ 




PREFACE. 


It would be impossible to exaggerate the importance 
of good wiring as an element in the prosperity and 
permanence of the various electrical industries ; and the 
writer of the present modest volume believes that his 
efforts to explain the true principles of good wiring and 
to point out the best methods will be welcomed cordially 
by electrical engineers, contractors, wiremen and the 
public generally. 

The idea followed in inditing these pages has been to 
•draw upon personal experiences ranging over a great 
many years, and to set forth in plain, simple language 
the things that must be done and the things that must 
be avoided. Every part of the subject is treated in such 
a manner that beginners, wiremen and others interested in 
the practical branches of the art of interior wiring can, 
with a little attention, understand readily why certain 
practices are preferable to others, and how a piece of 
work can be rendered safe and satisfactory. It is believed 
that practical advice from one who has himself tested by 
actual work and observation the value of every rule and 



IV 


PREFACE. 


suggestion here offered, will be very helpful. While 
much may seem novel, no statement is made that practice 
does not confirm, and no method is recommended that 
experience and common sense do not approve. 

There is as far as possible all avoidance of abstruse 
technicalities in the descriptions, and the divisions have 
been made with a view to an easier comprehension of the 

t 

different parts of the subject. A special series of draw¬ 
ings has been made for the book which will be appreciated, 
the author thinks, in several quarters ; and many of which 
have long been needed. 

It is hoped that a perusal of this book may lead many 
workmen forward to the study of other books that they 
have hitherto found too technical, so that they will then 
be able to see how close is the relation between good work 
and sound theory. All that the author asks credit for is 
an earnest desire, of which this little book is the ex¬ 
pression, for the perfection of an art to whose improvement 
he has devoted all his time and thought. 

AUGUSTUS NOLL. 


New York City, June, 1893. 


CONTENTS 


PAGE 


Chap. 

I. 

Introduction, .... 

3 

U 

II. 

General Considerations, 

5 

U 

III. 

Location of Conductors, 

8 

tc 

> 

HH 

Division of Circuits and Distri¬ 




bution of Current, . 

15 

a 

y. 

Loss of Electrical Energy in 




Conductors, .... 

24 

u 

VI. 

Plans, ...... 

30 

u 

VII. 

Conduit Wiring, .... 

33 

u 

VIII. 

Switchboards, .... 

49 

u 

IX. 

Appliances and Connections, 

51 

u 

X. 

Converter Work, 

53 

u 

XI. 

Overhead Wiring, 

63 

u 

XII. 

Fuse Wire, ..... 

66 

u 

XIII. 

Insulation, ..... 

70 

u 

XIV. 

Electrolysis, .... 

76 

u 

XV. 

Adverse Wiring Conditions, 

80 

u 

XVI. 

Theatre and Stage Lighting, 

85 

u 

XVII. 

Plans of Distribution, 

95 

u 

XVIII. 

Distribution of Light, 

113 




VI 


CONTENTS. 

Chap 

. XIX. 

Distribution of Labor and Hints 



to Foremen, . . . . 


XX. 

Preliminary to Rules, Electrical 



Data, etc., . . . . 

« 

XXI. 

Rules for Ascertaining Required 



Sizes of Wire, . 

u 

XXII. 

Energy—Power, . 

tc 

XXIII. 

Dynamos and Motors, . 

(( 

XXIY. 

Pulleys, . 

a 

XXY. 

Belting,. 

<< 

XXYI. 

Engines,. 

Cl 

XXYII 

Conclusion, . 


PAGE 

121 

125 

135 

140 

143 

150 

153 

155 

158 


HOW TO WIRE BUILDINGS. 


CHAPTER I. 

Introduction. 

1. In the science of electricity the question of 

/ 

“wiring” is liarclly considered, but in the appli¬ 
cation of electricity from a practical and commer¬ 
cial standpoint it is one of the most important and 
difficult factors. It embraces nearly every branch 
of what is termed “ construction work.” The 
student in electricity may have sufficiently mas¬ 
tered the theory of electrical currents, together with 
a knowledge of the different definitions and terms, 
to an extent that will enable him to “lay-out” 
wiring, on paper, in the form of a plan, showing 
the different circuits, sizes of wires, etc.; and while 
his work may be all that is desired in the shape of 
a plan, it will very often, even while the wires are 
being installed, fail of its purpose, owing to the 
conditions which exist in the building and which 
were not considered or known at the time of making 
the plan. The mere electrical student cannot thor- 




4 


HOW TO AVI RE BUILDINGS. 


oughly understand the “art of wiring,'’ because its 
essential features are purely practical, and can only 
be acquired by experience and strict observation. 

2. On the other hand, the practical wireman or 
beginner will make more rapid advancement if he 
will confine his studies to a general knowledge of 
electricity, sufficient to enable him to trace the 
direction of the current in dynamos, motors and 
appurtenances, and also in the wires, rather than 
fill his mind with all the different theories re¬ 
garding magnetism and electricity, which will 
only tend to confuse him and make the different 
methods and systems of wiring appear more diffi¬ 
cult and complex. When once the practical branch 
of wiring is sufficiently mastered, then will he be 
enabled to understand theory more easily, and he 
can gradually acquire a knowledge of the various 
terms, and of their relation to each other. 

3. I have in these pages endeavored to explain, 
and illustrate, the more important features con¬ 
tinually encountered in practical wiring, in as 
simple a manner as possible, eliminating all tech¬ 
nicalities, so that this book may prove of interest, 
not only to the student, but also to the workman, 
in the “art of wiring” as practically applied in 
electric lighting and kindred purposes. 


HOW TO WIRE BUILDINGS. 


5 


CHAPTER II. 

« ' 

General Considerations. 

4. Electrical “ construction work 1 ’ covers such 
a vast held, that, not to make the work too lengthy, 
nor to exceed our proper limits, we will only treat 
of that portion which relates to the “wiring” of 
buildings, and such other -branches incidental 
thereto, for electric lighting. It is, in this branch 
of the work, that the conditions are not hxed, and 
that those having charge of the work must depend 
largely on their own knowledge, judgment and 
ingenuity. There may be, for example, a change 
in the location or number of lamps ; change in 
location of dynamo (in the case of an isolated 
plant), and numerous other changes which are liable 
to occur, and for which no provision had been 
made, when the work was originally “laid out.” 

5. Ordinarily, the foreman in charge should lie 
competent: To draw a plan of each floor to be 
lighted; to understand and familiarize himself 
with the physical and other conditions, and from 
this data, proceed (leaving nothing to chance) to 
complete the plan of the wiring work and locate 



6 


HOW TO WIRE BUILDINGS. 


the cut-outs and switches; locate the wires, and 
decide on the method of distribution, and locate 
the feeding points between the Feeders, Mains, 
and Lamp Circuits; to decide on the most satis¬ 
factory percentage of loss of energy to be allowed 
in the different portions of the wiring system, so 
that the Difference of Potential, or pressure at the 
lamps, will practically be equal throughout the 
building. 

6. The foreman must also be able to compute, 
according to the per cent, of loss, the cross-section 
or size of wire necessary for use in the different 
parts of the wiring system; to determine the most 
satisfactory kind and length of fixture, and, when 
the wiring work is completed; to set up and run 
(in the case of an isolated plant) the dynamo, and 
connect same, with the wiring and the instruments 
usually provided; to compute the width of belt 
necessary and also the diameter and face of driving 
pulley if belted to a pulley on shafting, and in 
case of necessity run an engine ; and, finally, to 
locate and repair all defects in the wiring, and 
also slight defects in the dynamo, etc. 

7. These items form the necessary qualifications 
to ensure satisfactory and lasting results. The suc¬ 
cessful operation of the plant depends, to the great¬ 
est extent, on the manner in which the wiring was 


HOW TO WIKE BUILDINGS. 


7 


“laid out,” and electric lighting companies can 
trace the greatest part of the dissatisfaction on the 
part of their customers to the defective manner in 
which the wiring work was installed. 


8 


HOW TO WIRE BUILDINGS. 


CHAPTER III. 

Location of Conductors. 

8. It is sometimes the case in installing wires in 
buildings that, although the best grade of materi¬ 
als, of the several kinds usually employed for the 
work, was used, the results have been unsatisfac¬ 
tory ; the workmanship and appearance may have 
been all that could be desired, and yet in a short 
time after the current has been in use the work 
breaks down, and short circuits, grounds, leaks, 
etc., are of common occurrence. The fault is usu¬ 
ally due to the location of the wires. 

9. The following adverse conditions should be 
avoided as much as possible, and where it is im¬ 
possible to do so, proper safeguards, according to 
the condition, must be provided: Excessive moist¬ 
ure, atmospheric changes, extreme variations of 
temperature, extremely high temperature, gases, 
acids, lye, lime, cement, etc., and last, but one of 
the most important conditions, mechanical inter¬ 
ference. 

10. In dealing with the first class of conditions 
the best plan, of course, is to shun dangerous 



HOW TO WIRE BUILDINGS. 


9 


places, blit the location of the lamps may make it 
impossible. Generally, the best grade of materials 
and superior workmanship will lessen the chances 
of trouble, and with the high grade materials, as 
now manufactured, very little trouble should be 
experienced. 

11. By the use of conduits (see chapter on con¬ 
duits) and high grade moisture-proof wire, pro¬ 
viding a separate conduit for each wire, the results 
have been most satisfactory. Special care should 
be taken to have the joints, on both the wire and 
conduits, water-tight, and equally as well insu¬ 
lated as the remainder of the wire and tube form¬ 
ing the circuit. The cut-outs and switches should 
be grouped and located in places free from the 
deleterious conditions above noted. 

12. The lamps, sockets and fixtures should be 
designed with a view to protecting the electrical 
connections contained therein. Keyless sockets 
should be used, and the lamps should be controlled 
by switches. The lamp should be provided with 
an extra safeguard, arranged to exclude moisture 
and gas. The design of these is generally similar 
to that of a fruit jar, or bulb of thick glass her¬ 
metically sealed by means of rubber bushings and 
metallic cover. If the style of work is what is 


10 


HOW TO WIRE BUILDINGS. 


known as “open” or “exposed” work, the use 
of conduits, in many cases, will be unnecessary, 
but care must be taken to keep the conductors free 
from contact with the building, which can usually 
be accomplished by the use of suitable insulators. 

13. In dealing with conditions that come under 
the head of mechanical interference, care must be 
taken to locate the conductors and all appurte¬ 
nances used in the wiring work in such places that 
while they are of easy access to persons in charge, 
they are still inaccessible to inquisitive, unin¬ 
formed and malicious persons. 

14. When installing wires in a building in the 
course of erection, be careful to isolate and prevent 
contact with the work of other mechanics as much 
as possible. As the building is in a rough state, 
the wires must be handled with care to prevent 
abrasions in the insulation. The nature of the 
material forming the insulation will not admit 
of rough treatment, such as dragging along the 
rough floors, or across piles of brick and mortar, 
etc. In short, the wires should be so treated that 
the insulation covering them will not be bruised, 
cut or perforated in the slightest degree. In an 
otherwise perfect insulation the most minute dis¬ 
arrangement of its parts will often impair its use- 


HOW TO WIRE BUILDINGS. 


11 


fulness and permanence, and while, in some cases, 
the defect will at once become evident, still, in 
other instances, the fault may not appear until 
after the work has been in use for some time, when 
remedying the defect will cause expense and ex¬ 
treme annoyance, and will necessitate the cutting 
of the plaster on the side walls or ceilings. 

15. The destruction of the insulation, due either 
to natural deterioration, or other causes, is the 
greatest source of trouble in electric lighting (see 
chapter on electrolysis). Hence the use of inferior 
insulated wires is always false economy. 

16. Keep the work clear of and at some dis¬ 
tance from places where exposed wood work is to 
be fastened, such as the trim of doors, windows, 
chair-rails, picture mouldings, base-boards, etc., as 
these places will be plastered, and should the wires 
or conduits be located at these particular points, 
their liability to being cut by nails is very probable. 

17. When wires are placed under the floors or 
between partitions, they should be separated from 
each other and fastened beyond the reach of the 
floor nails or lath nails. Inaccessibility of the 
conductors should be avoided as much as possible, 
and concealment of same should only be resorted 
to where definite channels, such as conduits, have 


12 


HOW TO WIRE BUILDINGS. 


been provided. Do not sacrifice necessary safe¬ 
guards for a neat appearance, and do not “fish” 
electric light conductors, in the same manner as 
burglar alarm, annunciator, electric bell and such 
like conductors usually are. In the latter cases 
the wires are ‘ ‘ fished ’ ’ or threaded here, there and 
everywhere, so that they may be hidden from 
sight, but in the case of lighting circuits, no con¬ 
ductors should be inserted in a channel unless the 
exact condition of same is known. In this case 
you are dealing with horse-power , and nothing 
must be left to chance. Wires installed in build¬ 
ings must not be treated according to the apparent 
conditions. In every case a personal inspection by 
one experienced in this branch of the work is the 

only safe method. 

«/ 

18. Marble and tiled floors, etc., should be 
avoided as a place to locate wires whether con¬ 
duits are used or not. In cleaning such floors, sul¬ 
phuric acid is made use of; ancl materials of this 
nature absorb moisture, which will, in addition to 
the action of the acid, create another source of 
trouble. Regarding moisture and like conditions, 
no building for electric lighting purposes can be 
assumed to be dry. While it may have been dry 
at the time of installing the wires, the probability 
of this condition being changed is so great that as 




HOW TO WIRE BUILDINGS. 


13 


a safe rule it should be treated as damp and the 
corresponding grade of material used as though it 
were continually damp or wet, because the water- 
pipes may leak or burst, or the bath-tub or basins 
may overflow. 

19. When wires are encased in wood mouldings, 
the latter should consist of a grooved back board 
and a tight fitting cover, and in stores and similar 
places the ceilings should be kept clear of same 
as much as possible. A separate groove should be 
provided for each wire, and in no case should wires 
of the same or different polarity, forming different 
circuits, be placed in the same groove. That style 
of wiring should never be made use of in places 
where adverse conditions exist. 

20. In hotels, office buildings, residences, etc., 
locate all the appliances, main and feeding lines, 
in hallways or closets, so as not to have to enter 
rooms. The annoyance of interference, both to the 
inmates and workmen, may thus be obviated while 
the work is being installed. It will also obviate 
annoyance in the future, when repairs, renewals or 
alterations may be necessary. In workshops, fac¬ 
tories, etc., the wires are usually held to the ceil- 
ing by means of cleats, or fastened to porcelain 
knobs. The wires should always be located in 


14 


HOW TO WIRE BUILDINGS. 


such places on the ceiling as are clear of shafting* 
belts, etc., and where the work can proceed with¬ 
out interruption either to the wiremen or the hands 
and machinery employed on the premises. 



HOW TO WIRE BUILDINGS. 


15 


CHAPTER IV. 

Division of Circuits and Distribution of Cur¬ 
rent. 

21. When the building has been inspected and 
the various conditions in the different parts have 
been noted, the question of distributing the cur¬ 
rent then demands attention. The most impor¬ 
tant considerations are the equalization of pressure 
throughout the different lamp circuits, and to di¬ 
vide the circuits according to the manner in which 
the lamps will be used. In a building where the 
wires are to be concealed (new structure) the best 
mode of procedure is to locate the various closets 
or boxes for the reception of the cut-outs and 
switches. The location is governed by the number 
of lights, and size and shape of the building. Gen¬ 
erally from four to eight lamp circuits are carried to 
each box. The box should be, as nearly as possi¬ 
ble, in the centre of the space, the lamps in which 
are supplied with current by the circuits center¬ 
ing at this box. After locating the box and divid¬ 
ing the lights into circuits, the next step is to de¬ 
cide upon the method of dividing and connecting 



16 


HOW TO WIRE BUILDINGS. 


the main and feeder wires. The number of mains 
and feeders depends upon the size of the building 
and number of lights. Locating the connecting 
points between the mains and feeders depends upon 
the location and number of lights at each box or 
ramifying point, the distance between the various 
feeding points and the use of the lights. That is 
to say, in one part of the structure the lamps may 
be used continuously, and in another part only a 
few out of a great many may be used at any one 
time. The building should be cut up or divided 
into sections. Either each door or each side of the 
building should comprise a separate circuit, accord¬ 
ing to the size of the building (see chapter on ex¬ 
planation of distribution). If divided perpendic¬ 
ularly, one or more mains feeders are provided, ex¬ 
tending from the main switchboard in the dynamo- 
room to the central point between the feeding or 
connecting points on the line of the mains. The 
mains are usually run from the top to the lowest 
door, and at each door connections are made to 
wires which carry the current to the different lamp 
circuits. These door mains connect to one or two 
cut-out boxes. If they are located somewhat closely 
together, then only one set of main wires are re¬ 
quired; but should the distance between them be 
great, the door main must extend to a point mid- 


HOW TO WIRE BUILDINGS. 


17 


way between them, and again be divided, so that a 
branch from each will connect with the lamp cir¬ 
cuit independent of the other. 

Should the structure be composed of numerous 
floors, it will be the best plan, instead of connect¬ 
ing the main feeder from the dynamo-room to the 
mains in the central point, to provide a set of sub¬ 
feeders starting and connecting with the main 
feeders at its terminals, which should extend both 
ways and connect with the vertical mains at a 
point about one-quarter of the whole distance from 
the end. The idea of feeding in this manner is to 
equalize the lighting; that is, to balance the elec¬ 
trical pressure and the number of lamps in use, so 
that the variations constantly occurring will not 
affect the pressure to an extent where the life of 
the lamps will be shortened. 

22. The various systems of feeding all tend to 
this, as is shown in the plans (see chapter on same). 
From these it will be seen that the circuits are con¬ 
stantly being divided into smaller sections, so that 
the electrical pressure is practically the same 
throughout, and that each branch is, to a certain 
extent (electrically^, independent of the others. 

When “laying out” the feeding lines, not only 
should the work be done with a view to equalizing 
the pressure on the wire with the full load on, but 


18 


IIOW TO WIRE BUILDINGS. 


also for periods when only a few lamps are in use 
on any one branch, while in still another all the 
lamps were in use, so that the variation of jiressure 
on the conductors connecting with the few lights 
will be reduced to a minimum. To accomplish 
this, it is at times necessary to install two or more 
sets of feeders, connected at the same main con¬ 
ductors, but at different locations. Again, in other 
instances, such as a large isolated plant, or where 
the lighting covers a large area, it is necessary, in 
order to equalize the electrical pressure at the 
lamps, to provide and connect in the main feeder 
circuits regulating devices for controlling the pres¬ 
sure. 

23. In a plant where the loss of electrical energy 
in the conductors has been computed at a high 
rate, the pressure at the lamp will be at the rated 
amount only when all the lamps are in use; and, 
should only one-half be in use on any one section, 
the percentage of loss in that section will be only 
one-lialf of that in which all the lamps are in use. 
Consequently, the pressure on the wires in the sec¬ 
tion where only one-lialf are used will be greater 
than that at which it was rated, and the result 
would be excessive breakage of lamps. 

To overcome this defect is the function of the 
pressure equalizer. It may not be amiss to here 



HOW TO WIRE BUILDINGS. 


19 


explain what work the equalizer performs and the 
difference between it and a pressure regulator. 

24. A pressure regulator generally consists of 
a coil or numerous coils connected in the held or 
magnetic circuit and is usually (at the present 
time) controlled automatically, although regulat¬ 
ing instruments are constructed which can be gov¬ 
erned by hand. The coils are placed directly in 
the magnets, as in a compound wound machine, or 
by the use of magnets, all or any part of the coils 
can be thrown in or out of the held circuit. As the 
lamps are connected or disconnected on the various 
circuits, so will the strength of the pressure in¬ 
crease or decrease. As the pressure increases, the 
coil or coils are thrown in circuit, and, according 
to their resistance, the pressure is decreased until 
it is at its normal strength. The pressure is kept 
at a constant strength at the dynamo brushes. 

Should there be two or more independent sets of 
feeders carrying current to different parts of the 
structure, and on one set all the lamps be in use, 
the pressure at the lamps in this section would be 
normal; but if on another only a few out of a 
large number of lamps were in use, the pressure 
would be greater than that at which it was rated. 
The pressure required for the lamps, plus the per¬ 
centage of loss in the conductors (assuming no loss 


20 


IIOW TO WIRE BUILDINGS. 


on the line with only a few lamps in use), would 
equal the pressure at these particular lamps, and if 
the percentage of loss was computed at 10 per 
cent., then this amount would represent the in¬ 
creased pressure. To overcome this and equalize 
the pressure on this particular line without affect¬ 
ing the pressure on the other circuits, the equal¬ 
izer is used. It consists of a coil or numerous 
coils, divided in sections and connected to plates 
fastened to a slab of slate known as the equalizer 
face board. The coils are thrown in or out of the 
feeder circuit by means of a movable connecting 
plate fastened to a handle. In the case of a pres¬ 
sure regulator, the diameter of the wires is small, 
as they only carry the amount of current carried 
by the magnet wires, but the equalizer being con¬ 
nected directly in the circuit, it must have sufficient 
carrying capacity to carry the full amount of the 
current necessary, according to the number of 
lamps on the circuit, without heating. The size 
and length of the wire forming the coils depend 
upon the number of lamps and the percentage of 
loss allowed in the conductor. Where several sets 
of feeders are used, each set should be provided 
with an equalizer. The equalizer is connected on 
one side of the circuit only, in a similar manner to 
a one-pole switch. Throwing the coils in or out of 





HOW TO WIRE I3UILDIXOS. 


21 


the circuit is governed by the indications, as shown 
on the scale of the pressure indicators, which are 
provided and set in a place near the equalizer face 
board. The indicator is connected in the circuit 
by a set of pressure wires which connect with the 
circuit at the center of distribution, and as the 
pressure varies at that point, the amount of varia¬ 
tion will be indicated by the needle as it travels 
across the scale of the indicator, so that should the 
instrument indicate excessive pressure at the cen¬ 
ter of distribution, the current can be brought to 
normal strength by connecting or throwing in the 
circuit sufficient coils, the combined resistance of 
which will decrease the pressure to an extent where 
it will be equal to that required by the lamps to 
keep them up to their rated candle-power. 

25. To return to the subject of distribution again. 
The number of circuits should be as many as prac¬ 
ticable ; the greater the number, the less the vari¬ 
ation that can ensue. 

The system, as explained, is known as the 
“panel” or “grouping” system, and is princi¬ 
pally used in new structures, office buildings, 
hotels and such structures. In factories, stores, 
etc., the method of distributing the current in 
the main and feeders is the same, but the lamp 
circuit wires, instead of being grouped, are con- 


22 


HOW TO WIRE BUILDINGS. 


nected at the nearest point with a ceiling or floor 
main which extends through the whole length of 
the building. The lamp circuits terminate in a 
cut-out which is connected to the mains. The 
wires are either exposed or covered by grooved 
wood mouldings. In all structures where the con¬ 
ditions are such that all the lamps on certain cir¬ 
cuits are used at a given time, it is preferable to 
connect them to a special, independent feeder, so 
that the pressure on the circuits connected to the 
lamps used at intervals can be more nicely regu¬ 
lated. 

The lamps that are usually turned on and off at 
stated times, or which are only used on special 
occasions, are generally the entrances, hall, stair¬ 
ways, reading and waiting rooms, etc. 

26. In all wiring installations the public lights 
should form a separate circuit. 

The public lights are generally those in public 
parts of the building, and also generally include 
the engine-room, cellar, etc. 

All residences, hospitals, etc., should be pro¬ 
vided with a night circuit, having one or more 

lights in the hallway on each floor, and connected 

% 

in such a manner that they can be connected or 
disconnected from one or more places, and can also 
be connected to the burglar alarm and light auto- 


HOW TO WIRE BUILDINGS. 


23 


matically in a time of danger. This circuit is a 
great accommodation in case of sickness, sudden 
alarm, etc. 


24 


HOW TO WIRE BUILDINGS. 


CHAPTER Y. 


Loss of Electrical Energy in Conductors. 

27. The expression “percentage of loss,” when 
used in connection with electric lighting, signifies 
the amount of electrical energy expended in the 
conductors and is due to their resistance. The 
rate is governed by the local conditions, but, usu¬ 
ally, wiring connected to mains from central sta¬ 
tions is figured on a basis of two per cent, loss, and 
wiring for isolated plants at five per cent. loss. 
To a certain extent, it is governed by financial con¬ 
ditions, that is, the percentage of loss is increased 
in cases where fuel is cheap or when water-power 
is used. As a general rule for ordinary isolated 
plants it may be stated thus: Decrease the loss 
and the cost of maintenance is lessened, but de¬ 
crease the jiercentage of loss and the first cost is 
increased. It is preferable to slightly increase the 
first cost by wiring at a low rate of loss because the 
decreased cost of maintenance will more than offset 
the difference in first cost in generating the cur¬ 
rent by the saving in fuel. The liability to exces- 



HOW TO WIRE BUILDINGS. 


25 


sive lamp breakage is also obviated when the per¬ 
centage of loss in the conductor is low. 

28. The first cost, assuming the boiler, engine, 
etc., to be already installed, consists of the gener¬ 
ating apparatus and its appurtenances, wire, ap¬ 
pliances, fixtures, lamps and cost of labor for 
installing same. With proper care, the generating 
apparatus, its appurtenances, wire appliances and 
fixtures, will not depreciate to any considerable 

V. 

extent. Therefore, the cost of maintenance con¬ 
sists chiefly in the amount of fuel necessary for 
generating current and the renewal of lamps. 
The first item is governed by the amount of cur¬ 
rent required to maintain the rated candle-power in 
each lamp. (See formula electrical energy.) 

The renewal of lamps depends largely on the 
breakage due to the action of excessive current. 
When the pressure is normal, the action of the 
current in passing through the carbon is such that 
the carbon is gradually decomposed and disrupted 
to an extent that finally the carbon breaks. Under 
ordinary normal conditions the lamp will give con¬ 
tinual service for from 600 to 1,500 hours. This is 
termed “the life of the lamp,” but should the elec¬ 
trical pressure vary so that at certain times it is 
greater than the strength required, the carbon will 


26 


HOW TO WIRE BUILDINGS. 


be overtaxed; the strain will be too great, the dis¬ 
ruptive action will be increased and the carbon will 
become defective and weak, and usually in a short 
time it will break. The amount of coal consumed 
is governed by the amount of electrical energy 
generated in the dynamo, and if ten per cent, of 
the electrical energy is required to overcome the 
resistance in the conductors, then practically ten 
per cent, of the total amount of fuel used is the 
cost of carrying the current from the dynamo to 
the lamps. From this it will easily be seen that 
the question of percentage of loss in the conductors 
must be most carefully considered, not only from 
an electrical but also from a commercial stand¬ 
point. Another important consideration is to have 
the percentage of loss distributed properly in the 
different conductors forming the circuit. The most 
general and satisfactory method is, assuming the 
loss to be five per cent., to allow one-half per cent, 
in the lamp circuit, one per cent, in the door 
mains, one and one-half per cent, in the vertical 
mains and two per cent, in the main feeders. 

While the term “percentage of loss” indicates a 
loss of energy between the dynamo and lamps, 
commercially it is considered as the cost of trans¬ 
mission, and, if intelligently considered, will not 
be treated as a waste of power, but as a legitimate 


HOW TO WIRE BUILDINGS. 


27 


item in the cost of lighting. No energy can be 
transferred without loss or cost. 

29. To demonstrate the principle more clearly, 
assume a lamp located at a distance of 1,000 feet 
from the dynamo. The resistance of the lamp (the 
resistance of lamp is always figured at the time the 
lamp is hot, or at incandescence) is 90 ohms, and 
it requires, to bring same to its rated candle-power, 
a current of one-half ampere at 45 volts. We will 
decide to lose ten per cent, of the electrical energy 
in the transmission of the current from tlie dy¬ 
namo to the lamp, in the conductors. If the differ¬ 
ence of jiotential at the brushes of the dynamo = 45 
volts, the difference of potential at the lamp would 
equal 45 volts — ten per cent, loss = 41.5 volts. But 
we wish to get a pressure of 45 volts at the lamp , 
which is necessary to bring the lamp to its rated 
candle-power. Therefore, 45 volts only represent 
90 per cent/ of the pressure. Thus 50 volts = the 
pressure at the dynamo brushes. This lamp hav¬ 
ing a resistance of 90 ohms; 2,000 feet of wire 
being required to connect same with the dy¬ 
namo ; ten per cent, being the loss expended in 
the conductors, and 90 ohms representing 90 per 
cent, of the total resistance of the circuit, the 2,000 
feet of wire must equal, in resistance, ten per cent. 


28 


HOW TO WIRE BUILDINGS. 


of the entire circuit, which is 10 ohms. Now, to 
lind the electrical energy expended in the conduct¬ 
ors and lamp expressed in watts (see formula): 

= C = X A and C X E — watts = ]/z X 45 = 22% 

i? = 90 

watts expended in lamp, and % X 5 = 2% watts 
expended in conductor. Or, C 2 x R = watts. 

Therefore, 

.5 X .5 x 90 = 22.5 watts expended in lamp, and 
.5 X .5 X 10= 2.5 “ “ “ conductor. 


In both of the preceding instances it was shown 
that the lamp required one-half ampere at 45 volts; 
•consequently a greater pressure was required at 
the dynamo to allow for the “drop’’ in the con¬ 
ductors. In this last case it required 5 volts, 
making the difference in potential at the brushes 
of the dynamo 50 volts, the combined resistance of 
the lamp and conductors being 100 ohms. Con¬ 
sequently the current consumed on the entire cir¬ 


cuit = 


50 volts 
100 ohms 


= yz ampere. 


But this ampere 


is developed at a pressure of 50 volts. Therefore, 
it required more power in watts, as 50 volts X .5 




HOW TO WIRE BUILDINGS. 


29 


ampere = 25 watts = the power required for lamp 
and conductor. 

From this it will be seen that the question of 
percentage of loss must be carefully considered, not 
only from a financial, but also from an electrical, 
standpoint. 


80 


HOW TO WIRE BUILDINGS. 


CHAPTER VI. 

Plans. 

30. The plans generally used for showing elec¬ 
tric light wiring work are what is known as Floor 
and Elevation plans. 

The Floor plan represents everything as being 
Hat, and on it are .marked the outlets, showing the 
number of lamps to each, and whether from the 
side or the ceiling ; the size and location of the 
wires forming the lamp circuits and the lamps 
which are to be connected to each ;. also the size, 
style and location of cut-outs and switches. 

The Elevation plan should show the number of 
sets of feeders and mains, the exact location of 
points of connection between the feeders and mains, 
and between the mains and sub-mains which con¬ 
nect with the lamp circuits either at the grouping 
point or where the cut-outs are located along the 
ceiling, as in factories or in general open work. 
The style, size and location of main cut-outs and 
switches should also be shown. In the ordinary 
two-wire system it is usual to show only one wire, 
it being understood in this case that the wires 



HOW TO WIRE BUILDINGS. 


31 


forming the other side of the circuit will run par¬ 
allel with the one shown on the plan, and that 
the cross-section is to be the same. 

31. In formulating a plan of wiring it is best to 
be familiar with the nature of the structure, so 
that the wires may be fastened in places where the 
mechanical conditions are favorable. 

While the “runs” should be as straight and 
short as possible, still the drilling of walls and 
partitions must be considered. In some cases it is 
cheaper to lengthen the circuit; that is, run the 
wires at an angle to those already in place, so as 
to form a turn and run somewhat out of the wav, 
or so as to obviate the necessity of cutting through 
a thick brick or stone wall; or, in another instance, 
to have the wires free from the interference of 
steam pipes, leaks of pipes, etc. 

It is preferable to make an examination of the 
premises before laying out the work on the plan. 

The plan should be arranged to show all the 
different circuits and appliances as plainly as pos¬ 
sible. 

A good method is to designate all the different 
cut-outs and switches by a letter of the alphabet, 
and on a separate sheet or on the margin of the 
plan, refer to same. The quantity of each appli- 


32 


HOW TO WIRE BUILDINGS. 


ance, and the amount of each size of wire, will in 
this way be an easy matter to estimate. 

32. When the work is completed, the plans, 
together with any alteration, either in the number 
or change in location of lights and change of loca¬ 
tion or size of wire, should be returned to the com¬ 
pany. A report on the changes, and by whose 
authority the same were made, should also be 
submitted. 


HOW TO WIRE BUILDINGS. 


33 


CHAPTER VII. 

“ Conduit Wiring.” 

33. When concealing wires, either by threading 
them between the partitions, or under the floors, 
or embedding them in the plaster, so that when 
covered they are totally inaccessible, the insulation 
is subject to deterioration and impairment due to 
various causes which may disarrange the lighting 
system of the light and cause failure or a lire. 

It is well known that the best insulated wires 
will withstand the action of lime, cement, alkalies, 
etc., for only a short time. The insulation will 
then be useless for the purpose. The natural out¬ 
come is that the circuit must be rewired, which 
usually means but a choice of evils. 

The plaster must either be cut, or the carpets, 
floor, etc., must be torn up to get at the wires. 
The wires can be run on the surface and covered 
with wood moulding, but this is not desirable in 
decorated places. These same conditions confront 
us when additions or alterations are necessary. 
Buildings wired for so-called “future use” prove, 
in the majority of cases where it is proposed to 



34 


HOW TO WIRE BUILDINGS. 


use tlie wiring a few years after, to be unfit to turn 
the current on, and the re-wiring generally costs 
more than the original work. Tinkering with the 
wires already installed would simply be false econ¬ 
omy. The materials used in electric lighting are 
affected by conditions which are not considered in 
gas lighting, but there is no reason why the work 
should not be equally as permanent and successful 
as good gas piping. This can only be accomplished 
by arranging all the conductors and appliances in 
such a manner that the whole wiring installation 
is accessible, but defacing the walls and ceiling is 
objectionable and must not be attempted. 

34. It is therefore necessary to locate the wires 

«/ 

in places out of sight yet all accessible. To do 
this it is necessary to form channels in the walls 
and under the floors for the reception of the wires 
exclusively. The cheapest, safest and most prac 
tical method is to provide conduits and boxes for 
purposes of branching and as receptacles for the 
cut-outs and switches. These boxes are also used 
' for the purpose of withdrawing or inserting wires, 
and may be considered as a hand-hole, similar to 
a manhole used for underground work. 

The conduits not only form an extra mechanical 
protection to the wires, but also exclude those 
elements which generally render the insulation on 


HOW TO WIRE BUILDINGS. 


35 


the wires worthless. Ordinarily it is impossible, 
except at a great expense, to change the system of 
lighting from the two to the three-wire system, or 
vice versa , or, from 100 to 50-volt lamps. The use 
of conduits admits of any practical change either 
in the system or in the number of lights. 

Buildings can be equipped with conduits (instead 
of wiring) for future use, and the insertion of wires 
is unnecessary until the actual time of service, and 
at a very small increased cost. 

For electric lighting purposes, no wire should be 
inserted in undefined channels, such as between 
floor and partition, because the conditions existing 
in the channel are unknown; they may change at 
any, time, and the result is a matter of chance and 
peril. 

35. The conduit should be constructed of such 
materials as will meet the requirements of the pur¬ 
pose, and the diameter of the bore should be ample 
for tiie conductor. They should be installed in a 
manner somewhat similar to that of wire. The 
most essential features to be considered are ; the 
completeness of system as to points of accessibility 
and absolute continuity of the tubes or wire-ducts. 

The conduit system consists of joining together 
lengths of the tubes, using elbows where turns and 
bends are necessary. When the length or number 


36 


HOW TO WIRE BUILDINGS. 


of turns or bends in a circuit are such that the in¬ 
sertion of the wire becomes difficult, angle or 4 4 fish¬ 
ing 7 ’ boxes must be provided so that it will be an 
easy matter not only to insert, but to withdraw the 
conductor. Junction boxes, according to the direc¬ 
tion and number of branches, must also be pro¬ 
vided. The boxes act as a receptacle for the cut¬ 
outs, keeping them out of sight, and imparting a 
finished appearance to the work. 

The conduit must be continuous ; from outlet to 
outlet, from box to outlet, and from box to box. 
Care must be taken to have all joints, either at the 
coupling or the box, water-tight, and well insu¬ 
lated. The inner surface of the tube must be in 
alignment throughout; that is, no.shoulders or im¬ 
pediments should be created, so that the insertion 
of the wires can be done quickly and without 
trouble. In a system of conduits embracing all 
the favorable features, the insertion of wires in the 
conduits can be deferred until the building is act¬ 
ually completed. The cut-outs and switches can 
be inserted and connected at the same time. The 
metal parts will remain bright and clean, and the 
troubles usually encountered in new buildings, due 
to corrosive connections, are in this case obviated 

The insertion of drawing-in strings at the time of 
installing the tubes must not be relied upon. The 




Conduit Work. 



38 


HOW TO WIRE BUILDINGS. 


tube must be considered empty, and installed in 
such a manner that should the drawing-in string 
break, the insertion of the wires can still be easily 
effected. 

Where the conditions are adverse to ordinary 
wiring, the use of conduits .carefully installed will 
generally meet all the difficulties. 

36. The conduits and boxes should be located in 
the halls or public parts of the building as much 
as possible, so that additions and renewals can be 
made without annoyance to the tenants. The bends 
and turns should occur as near the ends of the lines 
of conduit as possible, it being easier to insert wires, 
more perfect control being had over the fish wire. 
The conduits should be so arranged that a point of 
entrance is obtained at each outlet, as shown in 
Fig. 1, so that the work of insertion may be quick¬ 
ly accomplished. It also admits of alterations 
being made quickly. 

The system of distribution is similar to the ordi¬ 
nary methods of wiring. A recess in the wall 
should be provided for the reception of the main 
and feeder line conduits exclusively, provided with 
a detachable cover throughout; or at a certain 
point on each of the different flows, exactly as 
shown in Fig. 2. 

In the figure showing tubes in recess A repre- 



HOW TO WIRE BUILDINGS 


39 ' 



Fig. 2.—Conduit Wiring. 

































































































































































































40 


HOW TO WIRE BUILDINGS. 


sents the main tube. B represents the main floor 
cut-out, inserted in a floor main junction box, O 
represents the floor mains which connect with the 
lamp circuits. Usually the main wires are large, 
which make it advisable to have the cover of the 
recess detachable the whole length. The main 
wires can be so arranged that a pair are run from 
the dynamo switchboard direct to each floor, or 
the system of distribution can be so arranged 
that the wires can be looped in the conduit, from 
floor to floor, thus relieving the conduit of the 
strain due to the weight of heavy conduct¬ 
ors. The connections can be made as shown in 
Fig. 3. 

In Fig. 3, A represents main floor boxes, one 
on each floor, to which are connected the con¬ 
duits for the main wires. The wires as seen are 
cut at each floor, so that instead of starting 
at A 2 and drawing the wires through the 
conduit to A 3 , it is only drawn from box to box, 
and the conductor is made continuous at the cut¬ 
out connection. Hence, if in the future it be¬ 
comes necessary to withdraw the wire from the 
conduit, between any of the floors, it can be 
quickly and easily effected. B represents the main 
feeder junction box with cut-out inserted, for 
means of connection between the feeder and main 


HOW TO WIRE BUILDINGS. 


41 



Fig. 3.—Conduit Work. 















42 


HOW TO WIRE BUILDINGS. 


wires. As this wire will generally have a large 
cross-section, it will be necessary to provide an 
angle-box at C (which is at the bend where the 
feeders assume a perpendicular position). The an¬ 
gle-box obviates the necessity of elbows, and at the 
same time performs the function of a “fishing 
box.” 

The lamp circuits are divided in a similar man¬ 
ner to that made use of in ordinary wiring. All the 
circuits are brought to a central or grouping point, 
and the conduits terminate at the box enclosing 
the cut-outs, as in the “Panel” or “Closet” 
method. Judgment must be exercised in dividing 
the circuits so that the run from outlet to outlet 
will not be too long or will not contain many turns 
or bends. 

37. One of the most simple and satisfactory 
methods of fioor wiring in conduiting, is shown in 
Fig. 4, which represents all the fioor main lines of 
conduits located in the corridor, and at a point near 
the ceiling. A represents single branch junction 
boxes, fitted with a branch cut-out, one of each be¬ 
ing located opposite to the room, whose lamps it 
controls. The lamp circuit is connected with it and 
is looped from outlet to outlet as shown in Fig 5, 
keeping each room on one independent circuit. 
The mains for the section of rooms will be looped 




HOW TO WIRE BUILDINGS 


43 










































44 


HOW TO WIRE BUILDINGS. 


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X 






I 




X 


Q 

£ 

c 


IQ 

6 

t— 


^ 77777777777777777777777777777 / 


















HOW TO WIRE BUILDINGS. 


45 


in a similar manner from A to A , so that provision 
is made for easy manipulation. B represents the 
main cut-out and junction-box for the section 
through which the floor main C connects with the 
section main ; D represents an angle-box, for use 
at the turn, and for making easy the insertion of 
the main wires in conduit C. E represents the 
main door junction-box and cut-out. 

By the use of this method, the jiressure on the 
wires can be equalized just as nicely as in the 
“Panel” system. This method tends to shorten 
the distances between feeding points, manipulation 
is easier, and while the cost of material is not 
increased, the amount of labor is considerably 
decreased. 

38. When the lighting is for general illumina¬ 
tion purposes, that is, when the lamps are turned 
on or off at the socket, as in office buildings, etc., 
the lamp circuits can be installed in various man¬ 
ners, as shown in Figs. 6 and 7. The advantages 
obtained are, that should the wire in the cut-out 
(cut-out link) fuse, it would only disconnect a por¬ 
tion of lamps located in any one room. Also, it 
will sometimes save material and time, by shorten¬ 
ing the length of the circuits, and avoiding turns 
and bends. 

39. The joints must receive the same care as the 


46 . HOW TO WIRE BUILDINGS. 


x a 

« 

das Pipe 

wm X 'OPtoOr X mm 

r 

a x 

To cut-out do^ 
on tfiis/7oor 1 

x £ 

^—^1/ 1 " 1 

R Tocut-offtX 

Boston Mis/toor 

a X 3 t y/ Tioor x a 

r w 

iX 

Gas Pipe 

X m 

To cu/out^it 
on Mis/toorJ 

R 

a* 2”*Moor x m 

Tocut-outfit 
on this floor T 

1 

MB X 

X _ 

To cut-out 

j~ 

- * J se Ftoor x - 

~ 

Si X 


F*ig. 6.—Conduit Work. 














HOW TO WIRE BUILDINGS. 


47 





tf&Ai UO/fflUVd' 


H 

<o 



Fig. 7.—Conduit Work. 











48 


HOW TO WIRE BUILDINGS. 


joints on the wire, and the conduits should be 
handled in a careful manner. In no case must a 
hole or break in the conduit be patched. 

Not only must the continuity of the conduit be 
maintained throughout, but care must be taken to 
maintain its circular form also. 

In concluding this chapter it may be stated in 
short, that the use of conduits afford the only safe, 
reliable, and permanent method of wiring for elec¬ 
tric lighting and kindred purposes. 




HOW TO WIRE BUILDINGS. 


49 


CHAPTER VIII. 


Switchboards. 

40. It is preferable to make a plan, to scale, 
showing all the appliances it is intended to place on 
the switchboard before constructing it, so that suffici¬ 
ent space and insulation may be provided between 
conductors of different, or even of the same polarity. 
The appliances and conductors should be so ar¬ 
ranged that, whether for renewals or repairs, the 
different circuits can be disconnected without dis¬ 
turbing the remaining circuits, and without jarring 
or dislocating the board. The faceboard should 
be constructed of materials that are fire and moist¬ 
ure-proof, such as marble, slate, etc. 

Sufficient sjiace should be allowed between the 
back of switchboard and the wall of the room for 
purposes of inspection, repairs, etc., and also that 
should the wall be damp, the switchboard will be 
free from contact, and will not have water accumu¬ 
late on it. Theatrical and converter switchboards 
should be provided with a covering either in the 
form of a door, or a roll, similar to that of a roller- 
top on a desk. 




50 HOW TO WIRE BUILDINGS. 

41. All switches and cut-outs should be equipped 
with a suitable name-plate, designating the partic¬ 
ular circuit they control. The name-plate should 
either be fastened on, or directly under, the ap¬ 
pliance. In all switchboards, especially those used 
in theatres, the switches, cut-outs and other ap¬ 
pliances, such as regulators, etc., should be arranged 
so that manipulations are quick and easy. Usually 
the best plan is to place the switches in proper 
order or sequence, such as 1st, 2d, 3d floors, etc., 
or Parquet, Balcony, Gallery, etc., in theatres. 

42. Dynamo switchboards should be so con¬ 
structed that all the instruments are in plain sight, 
and that the dynamo switches can be easily thrown 
in or out, and should be located as near to the 
machine as possible. 

The location of the switchboards should be such, 
that the plates or connecting parts on the appliances 
will not corrode or oxidize, due to the surrounding 
conditions. 


HOW TO WIRE BUILDINGS. 


51 


CHAPTER IX. 


Appliances and Connections. 

43. All connections, on appliances which form a 
part of the circuit, should be kept clean and bright. 
The stationary connection should be securely fast¬ 
ened; the sliding or movable connections should have 
sufficient surface, and bearing tension; and all metal 
parts should have abundance of carrying capacity so 
that undue heating will be obviated. The connec¬ 
tions should be properly covered and protected. 
All bases should be of porcelain, slate or similar 
material, and all parts should be so arranged that 
access is easy. Switches should preferably be con¬ 
structed in such a manner that arcing or excessive 
sparking at the connections is impossible. 

44. In joining or splicing wires, care should be 
taken to have the metal at the point clean where 
the splice is to be made. The connection must be 
firm and rigid, and thoroughly soldered and insu¬ 
lated. The splice or joint must be made in such 
manner that in swinging or bending the wire the 
solder will not crack or become loosened. In chap¬ 
ter Y was shown the relation of the resistance of 



52 


HOW TO WIRE BUILDINGS. 


the wire to the lamp circuit, and the amount of en¬ 
ergy expended in same, but it was assumed that the 
resistance was equally distributed along the line. 
Should the line or conductor contain an improperly 
made joint, that is, one that is loose or corroded, the 
resistance at that point might exceed the amount of 
resistance in all the rest of the line. The conse¬ 
quence would be an abnormal heating at the joint, 
which would gradually extend throughout the 
whole length of the circuit; the current required for 
the lamp would be consumed in generating heat, 
the candle-power of the lamps would decrease, etc. 

It is often the case that high grade wire is used, 
and still the insulation resistance may test low. 
Generally that is due to the careless manner in 
which the joint was insulated. 

The rule is to have the insulation at the joint or 
splice equal to that originally on the conductor. 


HOW TO WIRE BUILDINGS. 


53 


CHAPTER X. 

Converter Work. 

45. The converter is practically an induction coil, 
in which high voltage and a small amount of cur¬ 
rent are converted or transformed into low voltage 
and a large amount of current. The general method 
of constructing induction coils is : a spool having 
for its core a bundle of line iron wires ; a few lay¬ 
ers of comparatively coarse wire are then wound 
on the spool, and the ends turned out so that con¬ 
nections with battery or source of current can be 
made, over the coarse wire. Thoroughly insulated 
from this are wound a large number of layers of 
very line wire, each layer carefully insulated from 
the others. The coil nearest the core is the primary 
coil, and the outer, coil of line wire, is the second¬ 
ary coil. When the primary coil is connected to a 
few cells of battery, and the coil is equipped with 
a rapid make and break device, a powerful electro¬ 
motive force is created in the secondary coil. The 
iron core is used for the purpose of increasing the 
lines of force that pass through the coils, and is 
composed of a number of line wires, to avoid the 


54 


HOW TO WIRE BUILDINGS. 


waste or “Foucault” currents which would be 
created in a solid core, and which tends to make 
the coils act sluggishly. 

46. In the case of the converter, the coils are 
constructed in a manner directly opposite to that of 
the ordinary induction coil. The converter primary 
consists of a small wire and many layers, and the 
secondary coil consists of a large wire with a few 
layers. 

The amount of current in amperes supplied to the 
primary coil is small, but the voltage is high, and 
the current in amperes created in the secondary 
coil, is large, but the voltage is low. The size of 
the coil governs the difference of potential and the 
current produced, or, in other words, the fewer the 
number of layers on the secondary, the greater the 
current in amperes, and lower the voltage. 

The converter as applied in practice, is one of the 
most important discoveries appertaining to the art 
of electric lighting, and is destined, at an early 
date, to play an even more important part than it 
does at present. It is therefore essential that wire- 
men should familiarize themselves with the work¬ 
ings and construction of the various types of con¬ 
verters. They are usually located on the roofs, or 
sides of houses, on poles, or in the vaults of struc¬ 
tures where the underground system is used. 


HOW TO WIRE BUILDINGS. 


55 




Fig. 1 . —Converter Work. 



























































56 


HOW TO WIRE BUILDINGS. 


When placed outside of a structure, a double pole 
switch and cut-out should be inserted in the line at 
the point of entrance to the building. When the 
converter is located in the vault or cellar, the pri¬ 
mary wires should be thoroughly insulated and 
protected from leaks, grounds, short circuits, and 
mechanical interference or dislocation and at no 
point should the conductor, or the material sur¬ 
rounding it, touch the structure. The greatest care 
should be taken, at the point where the wires enter 
the building, to exclude gases, moisture, etc. The 
insulation directly on the conductor should be of 
the highest grade. The conductor should be in¬ 
serted in a conduit composed of insulating mate¬ 
rial, and all should be inserted in a galvanized iron, 
or such like, pipe. The iron pipe should be fast¬ 
ened to, but kept free from, the building by the 
use of strong iron arms, having a band of insulating 
material between them and the iron pipe as shown 
in Fig. 1. The inner tube or insulating conduits 
acts as a protection against the abrasion of the cov¬ 
ering directly on the wire, and insulates it from 
the outer iron pipe. It also admits of more free¬ 
dom in handling the circuit. 

A separate conduit and pipe should be provided 
for each wire, and should extend to a box contain¬ 
ing the main cut-out and switch. This box should 


HOW TO WIRE BUILDINGS. 


57 


be lire-proof and water-tight, and should be out of 
contact with the walls of the structure. Sockets 
should be provided for the entrance of the pipes, so 
that the connection between them will be rigid and 
tight. The box should be of ample size, fitted with 
a cover or door, which should be kept locked, and 
fitted with a panel of glass, so that inspection, 
without exposure, is possible. It should be located 
as near the point of entrance, and in as dry a 
jDlace as possible. 

The converter should also be located as near to 
the point of entrance as possible, and should be 
enclosed in a box, which should be constructed of 
fire-proof material. The box should be kept free 
from contact with the building, in a manner similar 
to the switch-box. It should completely enclose the 
converter. The roof of the box should extend some¬ 
what over the sides and act as a water shed, and 
ventilating holes should be cut in the sides. In 
short, all primary work, which is that part begin¬ 
ning at the point of entrance, up to and including 
the converters, must be kept free from contact with 
the walls or fioors of the building. 

47. The distribution of current is essentially the 
same as in low tension direct multiple arc systems, 
and the total loss in the wires must not exceed two 
per cent. The circuits can either be divided in 


Print#rt/ I feeders 


58 


IIOAV TO WIRE BUILDINGS. 








































































HOW TO WIRE BUILDINGS. 


59 


accordance with the rated capacity of the converter 
(providing a separate one for each circuit,) or, the 
circuits can be brought to, and connected with 
omnibus wires in the usual manner, and also the 
secondary of each converter connected to the same, 
in a manner similar to the connection of dynamos 
in multiple as shown in Fig. 2. Where converters 
are to be connected to wiring on the three-wire sys¬ 
tem two converters are necessary. The primaries are 
connected in the usual manner, but the secondaries 
are connected in series. The two outer wires con¬ 
nect, one on each terminal, and the middle or neu¬ 
tral wires connect to the wire between the convert¬ 
ers as shown in Figs. 3 and 4. Where the larger 
sized converters are used, they should be set on a 
platform, built up and insulated from the floor ; 
and the switchboard should be so arranged that 
the primary work is separated from the secondary 
work. It is preferable to construct two switch¬ 
boards, the backs facing each other. 

In a large converter plant, and where the lighting 
is such that the greater portion of lamps are in use 
only at stated times, it is the most economical to 
arrange the wiring and converters in such manner 
that these particular lamp circuits, including the 
converters for same, are only connected to the pri¬ 
mary circuit at the time of use. The primary and 


3 Wire Secondary Mains 


60 


HOW TO WIRE BUILDINGS. 



Fig. 3.—Converter Work. 





































3 Wire* I Secondary/ I Mains 



Fig. 4.—Converter Work. 


















































62 


HOW TO W r IRE BUILDINGS. 


secondary circuits of each converter should be pro¬ 
vided with a double-poled cut-out and switch ; and 
should more than one converter be connected, the 
primary circuit should, in addition to those for each 
converter, be provided with a main cut-out and 
switch. 

48. It is preferable, where converters are located 
in a building, to have all cut-outs located outside 
of the converter. 

In no case must the two wires forming the pri¬ 
mary circuit, be bared at the same time, and in 
close proximity to each other. In splicing or in¬ 
stalling work, only one wire at a time, should be 
bared. Care must be taken in handling same, so 
that the body does not complete the circuit. 


HOW TO WIRE BUILDINGS. 


63 


CHAPTER XI. 


Overhead Wiring. 

49. It is often necessary in isolated lighting to 
connect the wires in more than one building to a 
dynamo, which necessitates pole, or outside work. 
If the distance between buildings is not great, the 
best method would be to provide a separate line or 
feeder for each, and the wires can be fastened to 
the outside of, and suspended between, the build¬ 
ings. 

It is preferable to use the petticoated glass insu¬ 
lators, instead of the ordinary porcelain knot, for 
this style of work. They should be kept free from 
contact with the building, and allowance must be 
made for swinging, so that the wire will not strike 
the building. They should be separated sufficient¬ 
ly, i. e. y in case of sag they will not come in contact 
with each other. This also prevents the accumula¬ 
tion of snow or ice. Where the wires enter or de¬ 
part from a building, generally over a door or win¬ 
dow, they must be protected by an extra covering, 
such as an insulating tube, not only for the purpose 
of separating and insulating them, but also to act 



64 


HOW TO WIRE BUILDINGS, 


as a water shedder. The holes should be bored at 
an angle, having the lower point toward the out¬ 
side. 

50. In work of this kind, it is preferable to keep 
the two wires forming each circuit, next to each 
other in the same manner as the circuits were in¬ 
stalled in the interior, so that when the plant is 
turned over to the customer, his man, in charge of 
the work, will more easily understand the system 
of wiring. The liability of mistakes, when making 
changes, will be lessened. 

51. In pole line work, the poles should be as 
short as possible. In setting in the ground, the 
depth is governed by the nature of soil, the height 
of the poles, and the weight of the wire. Generally^ 
for a 30-foot pole, 4^- to 5 feet is sufficient. Should 
the ground be swampy, a good plan is to excavate 
widely and deeply, to admit placing a strong barrel 
in the hole, into which the pole is set. The barrel 
should be filled and packed with small stones and 
sand, and the whole covered with the dirt. This 
will form a suitable foundation should the poles be 
short and the weight of the wire not abnormal. 
The base of the pole should be about 8 inches 
in diameter, and the pole should taper somewhat 
towards the top. If the poles are to be longer than 


65 


HOW TO WIRE BUILDINGS. 

30 feet, a safe rule is to increase the diameter of 
the pole 1 inch for every increase of 5 feet in 
length, up to 40 feet; and 2 inches in diameter for 
every 5 feet increase in length thereafter. The dis- 
tance between the poles must also be considered. 
Chestnut wood is generally preferred, although 
cedar and Norway pine poles result satisfactorily. 

52. The cross-arms should be securely bolted to 
the pole, and about 6 to 8 inches be allowed be¬ 
tween wires. Care should be taken when fastening 
the wires to the insulators, which should be of the 
petticoated pattern, so that the ‘ ‘ tie wires ’ 5 do not 
cut the insulation on the wires. It is preferable to 
provide an extra protecting cover for the wires at 
all the insulators. 

53. The wires should be arranged so that the same 
wire will be fastened to the corresponding pins on 
each pole, throughout its entire length. The dis¬ 
tance between poles depends upon the weight and 
size of the wire. A fair average distance would be 
200 feet. 


» 


66 


HOW TO WIRE BUILDINGS. 


CHAPTER XII. 


Fuse Wire. 

54. The fuse wire is to an electric lighting system 
or plant what the safety valve is to a system of 
steam generation and supply. The wire for fuses 
is composed of an alloy of tin, lead, etc., and to 
properly perform its functions should never be con¬ 
nected in a circuit carrying in amperes more or less 
than the rated carrying capacity of the fuse wire. 
That is : never use a 10-ampere fuse in a 5-ampere 
circuit or vice versa. Never make any allowance in 
the carrying capacity of the fuse wire. It has al¬ 
ready been tested and standardized by the manu¬ 
facturers. 

55. The fuse wires are connected in the circuit 
by means of a cut-out block, and when grounds, 
crosses, or excessive leakage occur, the current in¬ 
creases to such an extent that the conductors be¬ 
come unduly heated, due to their resistance. The 
nature of the fuse wire being such that it will melt 
at a lower temperature than the copper wire, it will 
in the event of an occurrence of this kind, melt, 
thereby automatically opening or breaking the cir- 



HOW TO WIRE BUILDINGS. 67 

unit. If the fuse wire is too small, it will fuse un¬ 
necessarily, which is a source of annoyance ; but 
should the fuse wire be too large, it will only melt 
after the load becomes too great, at which time the 
line and dynamo are so hot that the insulation is 
affected, or the resistance of the copper wire in case 
of electrolytic action, will be greater than that of 
the fuse wire (making allowance for the difference 
of melting points), in which case the wire will melt 
and may form an arc. In the event of an occur¬ 
rence of a short circuit or heavy ground, if no pro¬ 
vision in the shape of fuse wires had been made, 
the line or armature would melt. 

The importance of using only fuse wires, that are 
standardized, is evident. 

Never assume, unless the fuse wires have been 
supplied by the same manufacturer, that because 
the cross-section is the same in the case of two fuse 
wires, their rated capacity or fusable point is the 
same. The fusing point of the wires is governed 
by the proportions of the different metals forming 
the alloy, and although both of the above-men¬ 
tioned wires may have had sufficient carrying 
capacity for the particular circuit, the fusing points 
may have been different. 

56. In the case of a short-circuit the fuse wire, 
even though somewhat larger than necessary, will 


68 


HOW TO WIRE BUILDINGS. 


melt, but short-circuits is not the only element to 
guard against. Leaks and grounds are just as liable 
to occur, and the rating of the fuse wire must be in 
accordance with these liabilities. To explain the 
function of the fuse wire more clearly, it may be 
said that if in a piping system for water, steam, 
etc., the pipes should be overloaded, they will 
break or burst at the weakest point. In a wiring 
system, instead of bursting, the conductor will melt 
at the point which is weakest. To prevent this 

i 

happening in the dynamo and conductors, is the 
function of the fuse wire. Its cross-section or car¬ 
rying capacity, therefore, is figured only for the 
current necessary for consumption in the lamps, 
and should any increase occur, the wire will at 
once melt and disconnect the circuit. The question 
of fuse wires should also be considered from a 
financial standpoint. Should they be too large, 
and a ground occur, the dynamo is not only gener¬ 
ating the current consumed by the lamps, but also 
that which is wasted through the ground, and 
should it be in a system in which the dynamo is 
already heavily taxed, this additional amount 
which is wasted, will cause an abnormal drop in 
potential, or still worse, burn out the armature. 
The only method, whose prompt action can be as¬ 
sured, is the use of fuse wires, the capacity and 




HOW TO WIRE BUILDINGS. 69 

fusibility of which has been carefully tested and 
standardized. 

57. The insertion of fuse wires in circuits, is of 
too great importance to be a matter of chance or 
guess-work, and wiremen should never use fuse 
wire or links, other than that supplied by the par¬ 
ticular company or contractor, in whose employ 
they are at the time, because the distance between 
the screws on the cut-outs may be greater or less 
than for those used by other companies. This will 
change the carrying capacity of the fuse wires. 
Or, again, the alloy may be different. 


70 


HOW TO WIRE BUILDINGS. 


CHAPTER XIII. 


Insulation. 

58. Conductors are insulated for the purpose of 
harnessing or controlling the current, so that it 
can be directed in a certain defined path, which is 
generally wire composed of copper. In addition to 
its inability to transmit current, the insulation 
should be absolutely moisture-proof, and, if possi¬ 
ble, fire-proof. 

Rubber, and compounds composed principally 
of rubber, are, for practical purposes, the best. 
Rubber is elastic, and can be bent without injury. 
Being moisture proof, it acts as a safeguard against 
the worst element of trouble (see Electrolysis). 
Although not fire-proof, it will withstand high 
temperature without melting. This material being 
also naturally delicate, is protected and strength¬ 
ened by an outside covering, which is generally 
composed of fibrous material, treated chemically, 
so that it becomes to a great extent fire-resisting. 
The outer covering is not relied on for its insulating 
qualities, but more, from a mechanical standpoint, 
as a protection against abrasions, etc. Experience 



HOW TO WIRE BUILDINGS. 


71 


and time has demonstrated that, protection against 
moisture, is a prevention of fire ; and the best re¬ 
sults for interior work, have been obtained when 
the wires were insulated by a material similar to 
that mentioned. 

59. To secure permanence, the quality of the in¬ 
sulation must be of the best, and absolute contin- 
uitv must be maintained. The minutest crack, 
bruise, or pin-hole is sure, sooner or later, to create 
trouble. It must be handled with the utmost care, 
and the small amount of extra time spent in care¬ 
ful handling, will more than offset the time and 
trouble that would be needed to locate and repair 
insulation damaged by carelessness. The manu¬ 
facture of high grade wire of this nature, appre¬ 
ciating the importance of the subject, use the ut¬ 
most care and vigilance in its manufacture. It is 
one continual round of inspection and testing, from 
the start to the finish. When the wires are made 
up in coils, they receive the final test, and if found 
to be up to the standard, are made ready for market. 
The same care is exercised in the packing and ship¬ 
ping, and if equal pains were taken after the wire 
left the manufacturer’s hands little trouble would 
be experienced, due to defective insulation. The 
greatest source of danger is the rough usage it 
receives at the hands of inexperienced or careless 


72 


HOW TO AVIRE BUILDINGS. 


\\ T ire-men. Another source of trouble is, insufficient¬ 
ly insulated joints or splices. When baring the 

Avire to make a joint, the insulation should not be 

« . 

torn off, or cut in a manner similar to whittling 
Avood. It should be cut at right angles to, and 
neatly severed from, the conductor, and then slit 
open between the points cut. It Avill then be an 
easy matter to remoA T e the insulation, without strain¬ 
ing it on either side of the exposed part. In solder¬ 
ing, care should be taken to keep the insulation 
free from the acid and flame. 

60. When the splice is made, it should be insu¬ 
lated in a manner equal to that on any other part of 
the line. This is usually accomplished by the use 
of a strip of rubber compound, wound or wrapped 
around the joint, starting at a short distance back 
from the splice, and on the insulation. In wrap¬ 
ping the tape it should be wound at an angle, so 
that each of the layers Avill lap over one-half of the 
preceding Avraps. This provides a double thick¬ 
ness. If the conditions are adverse, an extra wrap- 
ping should be provided, and placed over the first, 
in such a manner that the laps of the second cover¬ 
ing cross the laps of the first. The heat of the 
hand is generally sufficient to cause the material to 
adhere and form a solid mass. Over all should be 
placed a tape of linen or such material, impregnated 


HOW TO WIRE BUILDINGS. 


73 


with rubber. When taping* splices on exposed 
lines in a perpendicular position, the wrapping 
should be started at the bottom of the splice and 
worked towards the top. In this manner the tape 
will act as a shedder. 

61. In molding work, the grooves should be suffi¬ 
ciently large to admit the wire easily, without being- 
forced in. When fastening wires to porcelain in¬ 
sulators with tie wires, an extra wrapping of tape 
should be put over the wires at those points, and 
care taken, that the tie wires do not bruise or dis¬ 
rupt the insulation. The more recent styles of por¬ 
celain insulators obviate the use of tie wires, and 
for this reason are a great improvement. Forcing 
wires in or around sharp corners is not recom¬ 
mended, and should be done with the greatest care. 

When uncoiling wire, be careful not to get a sharp 
kink in it. Should a defect in the insulation of a 
coil of wire be discovered, the whole coil should 
be put aside and subjected to a test before any part 
is used. In new buildings especially, the greatest 
care should be exercised. Avoid having the wire 
either in coils, or strung out, lying on the floor, 
while using. The floor is generally covered with 
mortar, brick, and other sharp or rough materials ; 
mechanics are constantly moving about, and the 
fall of a brick, or a barrow wheeled over the wire, 


74 


HOW TO WIRE BUILDINGS. 


is generally all that is necessary to impair the in¬ 
sulation. The defect may not show at the time, but 
sooner or later it is bound to be the source of 
trouble. When passing wires through walls, hoors, 
partitions, etc., a tube of insulating material should 
first be inserted, so that there may be no danger of 
tearing the insulation as it is passed through. 

62. For pole line or outside work, a strong and 
durable weather-proof covering should be placed 
over the insulation. 

The quality of insulation can only be determined 
by tests, and practical application, but to form a fair 
estimate of the quality simply by inspection, in a 
general way, it may be said that: the insulation 
should be tough and lively, that is, it should not 
resemble leather in the quality of its toughness, but 
should possess more elasticity, and when stretched 
and suddenly released, it should quickly assume 
its previous shape. If when pulled in opposite 
directions, it parts without stretching, somewhat as 
dry putty or dough would, it is inferior. The best 
grades have two layers of insulation, an inner white 
or red, and an outer black, core, and an additional 
covering of braid or tape over all. The advantage 
of the special inner layer is the prevention of the 
oxidization of the conductor ; and should the outer 
layer become bruised or impaired, the wire is still 


HOW TO WIRE BUILDINGS. 


75 


protected by the inner layer. The best manner in 
which to make the superficial tests, as explained, is 
to cut a small strip of insulation from the wire, 
divesting it of the tape or braid. 

Another method of testing for toughness, is : 
Taking a piece of No. 14 wire insulated, twist 
and bend it, until either the wire or the insulation 
is broken. 

In a first-class insulated wire, the copper will 
break, and the insulation will remain intact. 


76 


IIOAV TO AVIRE BUILDINGS. 


CHAPTER XIV. 


Electrolysis. 

63. In discussing this subject, it will be treated 
only Avith a view of showing its relation to Electric 
Light Wiring. While it is really a part of the 
previous chapter, it Avas considered too vital to 
be merely mentioned. It is of the utmost import¬ 
ance that wiremen and others interested in con¬ 
struction work should be familiar with the subject. 

Wires are also insulated for the purpose of pre¬ 
venting electro-chemical action. The word ‘‘Elec¬ 
trolysis” means Electrical analysis, or analyzing 
with, or by, the use of electricity. All liquids, 
with the exception of oils, are fair electrical con¬ 
ductors, and under certain conditions even oil Avill 
lose its insulating qualities to a great extent. 

Insert the wires forming both sides of a battery 
circuit, each into a glass tube, closed at one end 
and nearly filled with water, invert same into a 
larger jar, into Avhich, water must also be poured. 
The larger jar should be so arranged that the wires, 
composed of platinum, will not come in contact 
with the Avater in same; the use of the platinum 



HOW TO WIRE BUILDINGS. 


77 


prevents oxidization of the terminals. In complet¬ 
ing the circuit, through the water, decomposition 
of the water ensues. Water being composed of 
hydrogen and oxygen, it will in short be 
found that these gases have been generated, the 
hydrogen in one tube, and the oxygen in the other, 
and in proportion to their relative quantities. The 
separation or decomposition is caused by the ac¬ 
tion of the current when flowing through the water. 

Instead of using platinum wire and two tubes 
and a jar, we will change the experiment somewhat. 
We will take a jar filled with water into which are 
placed the ends of two pieces of ordinary copper 
wire, connected to battery. When the current is 
turned on, the water completes the circuit. In this 
case not only is the water decomposed, but the 
copper also. The wire forming the positive pole 
will be decomposed and the atoms will be carried 
through the water to the negative wire. This 
action in electric lighting is sometimes termed a 
“partial short-circuit,” and if the resistance of the 
conductor, either liquid or metallic, is lower than 
that of the fuse wire, the latter will melt and so 
disconnect the circuit. 

64. The most common causes of electrolysis are, 
defective insulation on the wire ; joints insufficient¬ 
ly insulated, excessive and continuous moisture, 


78 


HOW TO WIRE BUILDINGS. 


etc. With insufficiently insulated wire located in 
or fastened to a damp or moist wall, tlie amount of 
current escaping or leaking may at first be very 
small, but the action of the current, and the oxide 
from the copper, in a short time render the insula¬ 
tion absolutely worthless. The leak increases, and 
the current flowing through the copper wires, which 
are immersed in water, will create the chemical 
action, as explained. The copper will be decom¬ 
posed, and dissolves away into the water. Copper 
oxidizes rapidly, and the wire at this point, will in 
a short time be wholly decomposed. The greater 
the current and the lower the resistance of the 
moisture, the quicker this will be accomplished. 

Where this defect occurs, the action is as follows: 
If the resistance of the moisture or liquid between 
the poles, is as low as, or lower than, the resistance 
of the fusible strip used in the cut-out, the result 
will be the same as in a short-circuit; that is, the 
fuse will melt. But should the resistance of the 
moisture be far greater than that of the fuse wire, 
the decomposition of the wire will gradually be ac¬ 
complished, and as it advances, the heat, and loss 
of electrical energy in the conductors increases, the 
lights become dimmer, and the carrying capacity 
of the wire decreases, to the jioint where it melts 
instead of the fuse wire in the cut-out. 


HOW TO WIRE BUILDINGS. 


79 


In other instances, the wire will be so decomposed 
and so thin that at a certain point it is as tine and 
sharp as an ordinary needle, and a slight vibration 





Figs. 1, 2 and 3 .—Electrolysis. 


of the building will cause the wire to part and an 
arc to occur. 

65. The foregoing proves the importance of prop¬ 
erly fusing the circuits, and using only the best 
grade of materials. The best and most effective 
method of obviating the danger, is to use conduits, 
and high grade moisture-proof wires throughout, 
providing a separate tube for each wire, and ex¬ 
cluding moisture at the joints, etc. 

















80 


HOW TO WIRE BUILDINGS. 


CHAPTER XV. 


Adverse Wiring Conditions. 

66. Where adverse conditions exists, such as 
moisture and gas, the best results have been ob¬ 
tained by stringing the wires, fastened to suitable 
insulators, on the face of the walls, etc. The in¬ 
sulators should be as few as possible. The fixtures 
and wires should be kept free from contact with 
the building. The cut-outs and switches should be 
located in a clean dry place, and to accomplish this, 
the length of the circuits must, if necessary, be in¬ 
creased. The fixture, if one is necessary, should 
consist of a metallic pipe, and the wiring of the 
fixture must be two heavily insulated wires. The 
end of the pipe toward the outlet should be closed 
by a cork, putty, or insulating compound. The 
socket and lamp should be enclosed in a water-tight 
globe. Key sockets should never be used, but all 
.circuits be controlled by switches. The fixture 
should from time to time, be treated to a coat of 
preservative paint. 

In fixtures placed on the outer walls of a build¬ 
ing, the stem or pipe should extend through the 



HOW TO WIRE BUILDINGS. 


81 


entire thickness of the walls, and the electrical con¬ 
nections be made in the interior of the building. 

O 

All shades on outside fixtures should be of the 
hood pattern, ancl be provided with an inner shell 
or cover, so that the socket and lamp connections 
are protected from the elements. 

67. If conduits are resorted to, the same general 
directions must be followed, and care must be taken 
to exclude moisture and gas from the interior of 
the tubes. 

Stables .—The chief trouble in stables is due to 
the ammonia which is generated in the stalls. The 
moisture and exposure also affect not only the in¬ 
sulation on the wures, but corrode all the metallic 
parts of the fixture and the line appliances. There¬ 
fore the weakest points are at the joints, sockets, 
cut-outs and switches, and connection between the 
fixture and circuit wires. 

Breweries .—The conditions are somewhat similar 
to those which exist in stables, and in some por¬ 
tions of the structure, excessive moisture exists at 
all times. In other portions, the temperature is 
extremely high, and in still other parts, very low 
temperature exists. The same care must be taken, 
as outlined in the general directions, and in the 
fermenting room, if the conditions are unusually 
severe, double petticoated glass insulators set on a 


82 


HOW TO WIRE BUILDINGS. 


bridge or collar, suspended from the ceiling should 
be used, and the wires fastened thereto. The 
bridge or collar should be treated to at least two 
coats of preservative, insulating paint. The fix¬ 
ture wire should be of the same size as that on the 
lamp circuit, and the lamp circuit should be con¬ 
trolled by a switch and cut-out only, located in 
some suitable place. For the mains and feeders, 
conduits are recommended. If conduits are used 
throughout, care must be taken to keep the interior 
of the tubes free from moisture, gas, etc. 

Oil Works , Etc .—If the conditions are such that 
the oil does not leak through the floor excessively, 
then a general observance of the succeeding direc¬ 
tions is all that is necessary. In some cases the 
buildings are of the ramshackle sort, and the oil 
leaks freely through the floors. Where the leak¬ 
age is thus excessive, the only safe method is to 
provide a continuous shedder, for the line and fix¬ 
tures, consisting of tin, heavily coated with non- 
corrosive paint. The hood or shedder should be 
suspended from the ceiling, and the conductors be 
kept free from contact with the building. 

Where explosive gases are generated, or where 
paints, naphtha, and such materials are used or 
stored, the conductors should be kept free from 
contact with the building, and be exposed as much 



HOW TO WIRE BUILDINGS. 


83 


as possible, care being taken to provide against the 
accumulation of gases, etc., at any point. The 
fixture wire must be connected directly to the 
lamp-circuit wires, omitting the cut-out. All the 
circuits must be controlled by a double-pole cut-out 
and switch only, and the same must be located 
where the conditions are most favorable. 

68. In all such cases as those mentioned, the use 
of conduits on the mains and feeders is recom¬ 
mended. In no case must wires be moulded or 
cleated. Either large porcelain knobs or glass 
insulators must be used. 

Insulated wires, of any sort, must never be im¬ 
bedded directly in plaster ; and where alkalies, or 
acids exist, an extra covering, such as conduit, 
must be provided. 

Avoid placing wires under tiled floors, etc. 
Floors of this kind are usually cleaned with sul¬ 
phuric acid, which being absorbed by the tile and 
cement, attacks the insulation. 

In prisons, asylums, etc., the wires, lamps and 
appliances must be inaccessible for the inmates, 
but the switches and cut-outs must be located in a 
place easy of access for those in charge. All the 
cut-outs and switches controlling particular circuits 
on the different floors should be located in a place 
and manner corresponding to the conditions on the 


84 


HOW TO WIRE BUILDINGS. 


other floors. This will tend to simplify matters, 
and will not confuse the attendant, when it is 
necessary for some reason to turn on the lights 
quickly. 


HOW TO WIRE BUILDINGS. 


85 


CHAPTER XYI. 


Theatre and Stage Lighting. 

69. In theatre wiring, the wires, cut-outs and 
switches should be located in places out of the 
reach of inexperienced or malicious persons, but at 
the same time of easy access to those having charge. 
The cut-outs and switches should be grouped in as 
few places as possible, so that the turning on or off 
of lights may be quickly accomplished. All the 
lights in the theatre proper and stage should be 
controlled by switches at the stage switchboard. 
The circuits controlling lights in the dressing- 
rooms, cellar, and such places, should also ramify 
or branch out at this point. 

The public lights, that is : the lights on the side¬ 
walk, entrances, lobbies, foyers, waiting-rooms, 
etc., should be connected to switches, all at one 
point, and controlled from the front of the house, 
usually in or near the ticket office, or foyer. These 
circuits should be connected with a separate feeder 
direct from the source of supply, and independent 
of the circuits for the lights in the theatre proper. 



86 


HOW TO WIRE BUILDINGS. 


70. The lights in the auditorium are located in 
the dome ; proscenium arch ; side-lights in the gal¬ 
lery, balcony, and parquet, and in the private 
boxes ; the front of, or face of the gallery ; bal¬ 
cony and boxes ; and on the stage. All the circuits 
for these lights, except the stage lights, are gen¬ 
erally connected to the same regulator. 

The lights for the orchestra or band, are placed 
in deep metal shades, painted green on the outside, 
and white on the inner surface, so that when the 
lights throughout the house are turned down, or 
dimmed, the glare of the music lights will not 
counteract the effect. They must be arranged so 
that the light is reflected on the music only. The 
method of distribution is generally as follows: 
Separate feeders, extending from the switchboard 
on the stage, are carried to the centre of each cir¬ 
cuit, at which point the feeder terminates into a 
double branch cut-out, and the lamp-circuit wires 
are carried to the different lamps on the circuit. 

A good plan is to provide a separate circuit, con¬ 
necting with a switch and cut-out at the stage 
switch-board with the : 

Gallery side lights. 

Balcony side lights. 

Parquet side lights. 

Gallery “face” lights. 


HOW TO WIRE BUILDINGS. 


87 


Balcony “face” lights. 

Private box lights, outside of dome lights, gen¬ 
erally two circuits ; proscenium arch lights, two cir¬ 
cuits. If, in addition to the side lights in the 
house, chandelier or ceiling lights are placed in the 
rear of each, a separate circuit for each floor should 
be provided, and run similarly to the side light 
circuit. 

71. The rate of loss in the conductors is usually 
computed at 5 per cent., and divided as follows : 
1 per cent, loss in the lamp circuit, 1| per cent, loss 
in the feeder from stage switch board to the centre 
of distribution of lamp circuit, and 21 per cent, loss 
in the feeders from the dynamo-room or other 

t j 

source of supply. The stage lights generally con¬ 
sist of the foot, borders, bunch, entrance, ground, 
projecting, and such other lights as may lie used 
for scenic or other effects ; and a few “working’ 5 
lights. 

72. The foot lights generally consist of three cir¬ 
cuits, provided with the plain red and green, or 
blue glass bulbs, respectively. The position and 
construction of the fixture or reflector, and the 
lamps, should be such that the lamps are out of the 
line of sight, and the reflector so placed that the 
view from the auditorium will be wholly unob- 


88 


HOW TO WIRE BUILDINGS. 


structed. The lamp should be placed close to the 
reflector, and in such a manner that the light is 
reflected on the stage. In addition to the electric 
lights, provision- is made for gas lighting, and 
as the space is limited, the work should be so 
arranged, that in the event of the gas being lighted, 
the excessive heat will not affect the electric work. 
A satisfactory method is to construct the foot lights 
in a manner similar to that shown in Fig. 1. The 


lamp 

Socket 

MoiMnig 

Timber 



Stage floor 


Has Pipe 


Fig. 1.—Theatre Lighting. 


work is located under the stage, where dislocation 
is improbable, and is securely fastened so that only 
the bulbs of the lamps are visible. The work is 
covered and protected by heavy sheet tin, and holes 
are cut to correspond with the entrance of the 
sockets. 

This method will allow of placing a large number 
of lamps in one row. The three circuits are so 
arranged that the colors will alternate. 









HOW TO AY I RE BUILDINGS. 


89 


Another method is, placing the wires on the out¬ 
side of the reflector, having a frame work of wood, 
and placing the lamps at an angle, as shown in 
Fig. 2. These circuits are connected to the regu- 



Fig. 2.—Theatre Lighting. 


lating device, either separately, or arranged so that 
one regulator can be used for either, and the num¬ 
ber is governed by the width of the opening— 
usually as many as can be placed without crowd¬ 
ing. The inner surface of the foot light reflector 
should be coated with either white paint or lime. 

73. Border lights are rows of lights located in a 
reflector, and suspended between the curtains in 
the “ flies,” and high enough to be out of the sight 
of the audience ; they are used for lighting the 
body and back of the stage, scenes, etc. The 
reflector is formed to throw the light in the direction 
mentioned, and also prevents the light-giving 
medium from being seen in the front of the house. 





90 


HOW TO WIRE BUILDINGS. 


Each border usually consists of one row of plain 
glass bulbs, and the number of rows and lamps on 
each is governed by the width and depth of the 
stage, and the number of side entrances. Usually 
live rows are employed, and the two front, and the 
three rear borders are connected to separate regu¬ 
lators. At the opening, or front of the reflector is 
placed a wire screen, to protect the lamps and also 
acts as a fender in dropping or raising curtains. 
Each border consists of one or two separate cir¬ 
cuits, and the fixture is connected to the feeder bv 
means of flexible cables, the ends of which termi¬ 
nate in connecting plates in the form of a plug, 
which corresponds with a receptacle in the con¬ 
necting block, to which the wires from the switch¬ 
board are connected. Where two circuits are 
required, the lamps are connected alternately. 

74. Bunch and entrance lights are used for light¬ 
ing the entrance, or for lighting a particular part 
of the stage, when the remainder of it is in dark¬ 
ness, etc., and also for general illumination. 

The bunch lamps are usually placed on an iron 
fixture, arranged so that they can be raised or 
lowered or turned in any direction. The entrance 
lights are usually lamps placed on a strip of wood 
in the shape of a row of lights. The connections to 
the circuit are similar to those of the border lights. 


HOW TO WIRE BUILDINGS. 


91 


a receptacle for connections in the floor being 
provided on each side of the stage and at each 
entrance. These pockets or floor receptacles must 
be fitted in such manner that moisture is excluded, 
and constructed of fire-resisting material. 

The circuit from the switchboard is located on 
the ceiling under the stage, and is not connected 
to a regulator. 

75. Ground lights or rows, are constructed in a 
manner similar to the entrance rows, and are used 
for illuminating the back of hedges, water-falls, 
platforms, balconies, etc., in the scenery, and are 
laid upon the floor of the stage, at the point to be 
illuminated. The receptacles used for the bunch 
lights are made use of for these. All the stage 
fixtures are portable, and the arrangements for 
connecting and disconnecting must admit of being 
quickly accomplished. 

76. Projection lights are used for special pur¬ 
poses, such as throwing a beam of light in the 
shape of a streak of lightning across the stage, or 
directing it on a person, or object, or to suggest 
moving water, etc. The projection light consists of 
an arc light and suitable resistances, and is specially 
designed for this class of work. The wires from 
same can be connected with the incandescent wiring 


92 


HOW TO WIRE BUILDINGS. 


system used in the theatre. The lamp is provided 
with screens, lens, light filters, etc., and special 
appurtenances for lightning effects. The fixture is 
portable and the reflecting portion is arranged so 
that it can be turned in any direction, or raised or 
lowered. The flexible cable, used for connecting 
the lamp with the system, is similar to that used 
for border and bunch lights. The connections and 
locations are temporary, as the lamp is carried 
from one point to another according to its uses. 

| There is, however, a permanent ’line or circuit, 
carried from the stage switchboard to a connecting 
block, located in the front of the gallery. A pro¬ 
jecting lamp is used at this point to throw light of 
different colors on the ballet, or other quickly 
moving objects on the stage. 

77. In addition to the lights mentioned, others 
of a temporary character, are used for special pur¬ 
poses, such as chandeliers, newel posts, candelabra, 
hearth, moon, sun, etc. The fixtures for the first 
three are constructed of wood. The hearth lights 
represent a fire in the grate, etc., and are usually 
ordinary white glass lamps, placed in a receptacle 
representing a grate, and the grate is covered with 
red paper or mica. The fixture which represents 
the moon or sun, is constructed ordinarily of wood, 
in cylindrical form, a circuit of red and a circuit of 


HOW TO WIRE BUILDINGS. 


93 


ordinary lamps are placed therein, and the face of 
the cylinder is generally of tinted glass, sometimes 
formed and marked to represent the object. Each 
circuit is connected with a toning device, so that 
any tint may be obtained. By the use of the ton¬ 
ing device, representations of setting sun or rising 
moon will be faithfully borne out. The lamps must 
be located at a distance from the face or glass, so 
that spots of light or the shape of the carbon will 
not show. 

Nearly all the materials used on the stage for 
theatrical purposes are flimsy and highly inflam¬ 
mable, and the conditions are such, that a fire once 
started will gain rapid headway. The work of the 
stage hands in setting scenes, etc., is done in a 
hasty manner. It is therefore necessary to provide 
materials and to locate them in such a manner that 
they will withstand the existing conditions ; and 
care should be taken in fastening permanent cir¬ 
cuits, that they are not on temporary structures, 
liable to change. 

The switchboard should be constructed, as far as 
possible, of hre-proof materials, and the whole 
should have a covering similar to the flexible roller 
top used on desks, lined with asbestos, etc., so that 
when the switchboard is not in service, it prevents 
interference with appliances, and also acts as a 


94 HOW TO WIEE BUILDINGS. 

safeguard against falling objects, water, etc. The 
switches, cut-outs and regulators should be pro¬ 
vided with a suitable name plate, and be so located 
on the board that connections with the lamp cir¬ 
cuits can easily be made to provide for the various 
combinations necessary in this class of work. At 
the top of the board should be placed a pilot lamp, 
from each circuit, to act as a guide for lighting or 
toning purposes. 


HOW TO WIRE BUILDINGS. 


95 


CHAPTER XYIL 


Plans of Distribution. 

78. All circuits should be so distributed and con¬ 
nected throughout a structure that practically the 
pressure or difference of potential will be the same. 
It is often the case that the total amount of loss is 
small, but incorrectly divided ; that is, the greater 
part is allowed in the lamp circuit or sub-feeder, 
when it ought to have been allowed in the mains or 
feeder, or vice versa. 

Assuming 5 per cent, to be allowed in the con¬ 
ductors, it is generally best to distribute the loss as 
follows : 1 per cent, in the lamp circuit, 1| per cent, 
in the mains, and 2i per cent, in the feeders. 

The chance of having all the lamps on any one 
lamp circuit in use is greater than the chance of 
having all the lamps connected to a main in use ; 
and a small loss in the lamp circuit, will allow of 
placing a few additional lamps on those circuits 
without appreciably affecting the whole wiring 
system. The method of distribution is governed 
by the manner in which the lamps are to be used. 
In some instances, the lights are in use continuously; 




96 


HOW TO WIRE BUILDINGS. 


in others a certain proportion are in use at any 
one time, and in still others, certain sections are 
used at stated times. The distribution is therefore 
guided by these conditions. The best results are 
secured when a separate feeder is provided, for the 
separate sections having different conditions of 
lighting. 

79. All diagrams given here will show only one 
wire, unless otherwise mentioned, and may be used 
for the 2 or 3 wire system. 

Fig. 1 represents a cut-out box, either in a panel 
or closet located in the centre of its lighting area, 
and shows the connection therewith of the floor 
mains, which are connected with the vertical mains. 

Fig. 2 represents a main and feeder, and more 
particularly the various methods of distributing 
from the mains to the different ramifying points or 
panels. A represents the feeder from the switch¬ 
board in the dynamo room, connecting with the 
mains B at the point X, which is, in this case, the 
main central point of lighting ; and the lamps are 
figured as being at a distance equal to that between 
the switchboard and X. B and D represent the 
vertical mains, and if the lights are evenly divided 
on each floor, the distance is equal to one-quarter 
the total length, B and D connect with floor mains 
at each floor. On the 4tli floor M and M represent 


lamp Circuits 


HOW TO WIRE BUILDINGS. 


97 



) > 
> ) ) 


> , > 


Fig. 1 .— Plans of Distribution. 

























98 


HOW TO WIRE BUILDING'S. 


the lioor mains connecting with the cut-outs of the 
lamp circuits. On the 3d floor, to equalize the 
pressure, on account of two distributing points, the 
floor mains are again divided, as shown. On the 
second floor S and S l each represent a floor main, 
and are necessary to equalize the pressure on ac¬ 
count of the difference in the number of lights at 
each box, and the distance, the box y l being quite 
close to the feeding point. 

On the 1st floor is shown a method which should 
be avoided, because it is impossible to equalize the 
pressure. If the pressure at the lamps from box y 1 
is normal, the pressure at the lamps from box y 
and y l would be above normal, and, on the other 
hand, if the pressure at the lamps from y is normal 
that at the lamps from box y x and y 2 would be 
below normal. We therefore have a choice of two 
evils, running the majority of lamps below their 
rated candle-power, or, increasing the pressure, and 
lamp breakage. 

Fig. 3 represents a main and feeder system some¬ 
what similar to that shown in Fig. 2, except that 
the floors are greater in number. F represents the 
main feeder, connecting with the sub-feeders F l and 
F* at the point A. F 1 and F 2 extend from A , and 
connect with the main feeders c at the points I) 
and E. M represents the floor mains connecting 


HOW TO WIRE BUILDINGS. 



B 



ys y 7 Y 



Fig. 2.—Plans of Distribution. 































100 


HOW TO WIRE BUILDINGS. 


with, the lamp circuits. In large buildings the 
feeder systems, as shown in Figs. 2 and 3, can be 
provided, for each side of the building. 

Fig. 4 represents a plan of floor lighting, used in 
factory or general exposed work. A represents the 
main feeder, connecting with the sub-feeders B and 
B'\ at the point Y the sub-feeders connect with 
the main wires C and C 1 at the point X, which in 
turn connects with the lamp circuits L . Fig. 5, 
represents a system of distribution somewhat 
similar to that shown in Fig. 4. In Fig. 5 the 
wires forming both sides of the circuits are 
shown. This method is made use of where all the 
lights on any circuit are used at the same time, and 
are turned on or off by means of switches. This 
method can be applied when lighting large spaces, 
such as sheds, depots, etc. A represents a main 
feeder forming one side of the circuit, and its car¬ 
rying capacity is computed at the total number of 
lights, and connects at B with A A, which is the 
main wire forming one side of the circuit and con¬ 
nects with the wire forming that side of the lamp 
circuit on each circuit at the point E. S and 8 l 
represent the wires forming each side of the lamp 
circuit. C l C* C° C 4 are divisional mains forming 
one side of the feeder circuit and connecting with 
S 1 at the points K. It will be seen that the feeder 


HOW TO WIRE BUILDINGS. 


101 



Fig. 3.—Plans of Distribution. 







































102 


HOW TO WIRE BUILDINGS 




' >* 


























HOW TO WIRE BUILDINGS 


103 


A, and mains A A and the lamp wires S , form one 
side of the entire circuit, A and A A being common 
carriers to all. On the other side of the circuit S 1 
forms one side of each lamp circuit independent of 
each other, and the feeders marked C l (7 2 (7 4 are 

connected to S 1 and also independent of each other. 
At the terminals of the feeders are placed single 
pole switches, by means of which any of the cir¬ 
cuits can be connected without affecting the other. 

Fig. 6 represents a system somewhat similar 
to that shown in Fig. 5, except that in Fig. 5 
the feeders were connected at the centre of the 
length of the mains. In this case, sub-feeders 
are necessary, due to increased length, so that the 
pressure at the point X in the mains would equal 
that at the point Y. The method of connecting 
the lamps, or throwing them in or out of circuit, 
is the same as explained in Fig. 5. 

Fig. 7 is somewhat similar to Figs. 4 and 5, 
except in this case two separate feeders are pro¬ 
vided for the purpose of equalizing the pressure, 
and forming two separate circuits of each row of 
lamps, each circuit being independent of the other, 
on the same row, and also of those on the other 
row. One side of the lamp circuit wire is dis¬ 
connected at the middle, and each half is fed or 
connected to a separate divisional feeder. The 


104 


HOW TO WIRE BUILDINGS. 




































HOW TO WIRE BUILDINGS. 


105 



C* 


6 * 


C' 


j 

j 


A 


A 


G*C 3 C* 


C' 


Fig 6.—Plans of Distribution. 
















































106 


HOW TO WIRE BUILDINGS. 


method of throwing in or out of circuit by switches 
is similar to that as described in Fig. 4. 

Fig. 8 represents a system of distribution ap¬ 
plicable to large isolated plants, and by a few 
alterations in the method can be used for central 
station distribution. (The diagram shows a “fiat” 
plan). In large hotels the lighting conditions are 
constantly varying ; that is, all the lights in one 
section of the building may be in use at one time, 
and most of those connected on the feeders in the 
other sections not in use, and vice versa. Conse¬ 
quently the pressure on the wires is undergoing 
variations constantly, the result of which would be 
excessive lamp breakage, unsatisfactory service, 
etc. Under certain conditions it is not practical to 
wire at a low rate of loss, on account of the im¬ 
mense increase in first cost. The interest on the 
investment will more than offset the small addi¬ 
tional cost of pressure equalizers and the lost 
energy in same. 

Therefore, when the conditions exist as stated,, 
the conductors are installed at a higher rate of loss. 
In the diagram, F l to F* represent the vertical 
feeders, connecting to the mains and fioor mains, 
in the different sections of the building. The dia¬ 
gram also shows the different methods of feeding, 
which can be employed in each section. K repre- 


HOW TO WIRE BUILDINGS. 


107 



Fig. 7.—Plans op Distribution. 





























































108 


ITOW TO WIRE BUILDINGS. 


sents a ‘ ‘ crib ’ ’ to which all the different sectional 
feeders connect. E to E* represent main feeders 
connecting to the “crib” and extending to the 
dynamo switchboard. On the wire forming one 
side of each is connected a pressure equalizer, con¬ 
necting with the crib at the point where the main 
feeders connect; and, extended to the dynamo 
room switchboard, are run a pair of wires for each 
feeder, which are connecting with a pressure indi¬ 
cator. As the pressure varies at any of the feeder 
points on the “ crib,” the same will be indicated on 
the instrument and by throwing coils of the equal¬ 
izer, out or in, the pressure can be maintained at a 
certain point. 

Fig. 9 shows the method of connection, at 
the switchboard, with the dynamo and feeders. 
A and A A represent “Bus.” wires which act as the 
main or trunk line. Connected to this, are the 
different main feeders, and the leads from the 
dynamos. A pressure indicator is connected with 
the “Bus.” lines, to indicate the pressure in that 
part of the wiring installation. On the positive 
dynamo lead is placed an ampere-meter. 

The negative wires of the feeder circuits are con¬ 
nected to the “Bus.” bar A. The positive feeder 
wire terminates and connects to the faceboard of 
the equalizer, and from another connection on the 


HOW TO WIRE BUILDINGS. 


109 








































































110 


HOW TO WIRE BUILDINGS 


J $ 






0 ) 


Fig. 9.—Plans of Distribution. 


































































HOW TO WIRE BUILDINGS. 


Ill 


equalizer faceboard; and connecting with A A of 
the u Bus.” bar, is run another wire, equal in cross- 
section to that of the feeder. The equalizer and 
pressure indicator of each feeder circuit should be 
placed directly over each other, so that when 
throwing coils in or out of the circuit, the effect 
can be noticed. It will also tend to simplify mat- 



Fig. 10.—Plans of Distribution. 

Fig. 10 represents the coils and method of con¬ 
nections, in the equalizer, and to the feeder, and 
“Bus” bar or wires on the dynamo switchboard. 


























112 


HOW TO WIRE BUILDINGS. 


Assuming each coil to have a resistance of 1 ohm, 
and that there were 10 coils, it will, from the con¬ 
nections, readily be seen how the resistance can be 
varied. 


HOW TO WIRE BUILDINGS. 


113 


CHAPTER XVIII. 


Distribution of Light. 

80. In locating lamps, they should be so dis¬ 
tributed, that each lamp performs its equal share 
of the lighting, and is so located that, if the 
candle power of each lamp is the same, the 
diffusion of light will be equal, and if the number 
of lamps is sufficient, a space can be illuminated 
in such manner that the light is practically equal 
throughout. 

The number of lamps is governed by the space 
to be lighted, the purpose for which the structure 
is used, etc. 

The practical unit of light is the 16 candle-power 
lamp, and for ordinary illumination, one 16 candle- 
power lamp for every 100 square feet, suspended 
about 8 feet from the floor, is allowed. By 100 
square feet is meant a space 10 ft. x 10 ft., or 
8 ft. x 12 ft., etc. The amount of light, on this 
basis, is allowed only when the conditions are such 
that ordinary illumination is required, as in sheds, 
depots, walks, etc., and where close inspection of 
materials, etc., is not necessary. In waiting-rooms, 



114 


HOW TO WIRE BUILDINGS. 


ferry houses, etc., the allowance is generally one 
16 candle-power lamp to every 75 square feet. In 
stores, offices, etc,, for ordinary lighting purposes, 
60 square feet is the usual allowance. 

81. Fig. 1 represents the ideal method of dis¬ 
tribution, but in practice is objectionable, where 
pendants from the ceiling are used. When the 
lamps are located close to the ceiling and a fixture 


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Fig. 1.—Distribution of Light. 


or finish, corresponding to the surroundings, is 
made, the effect is very good. In the diagram, 
assuming the space to be lighted is 50 ft. x 50 ft., 











HOW TO WIRE BUILDINGS. 


115 


and the candle-power of the lamp is 16, to find the 
number of lamps necessary, 50x50 = 2500 ft 100 = 
25—16 candle-power lamps. Dividing the ceiling in 
squares of 100 ft. or 10 x 10 and placing a lamp in 
the centre of the square, each light will have the 
same amount of space to light, and the lamps will 
be an equal distance from each other. 

If in the same space, it is intended to place two 
lamps in a cluster, to obtain an even diffusion it is 


12 6’ J2'6" J2 ‘6" < 12 6 


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Fig. 2.—Distribution of Light. 


necessary to use 32 lamps instead of 25 as in the 
first case. 









116 


HOW TO WIRE BUILDINGS. 


Fig. 3 shows a method of distribution, each out¬ 
let having a cluster of four lamps instead of single 
lamps. 



Fig. 3.—Distribution of Light. 


Dividing the lamps into clusters, requires more 
lamps for the same space, and the greater the 
number of lights at any one point, the more uneven 
will the lighting effect be. 

82. Lighting from the side wall is not as econom¬ 
ical as from the ceiling, and the results are limited. 
Ordinarily side lights are only used to equalize the 
diffusion of light, when the lighting from chande- 








HOW TO WIRE BUILDINGS. 


117 


liers, or in a small room, and where a fixture from 
the ceiling will impart a crowded appearance. For 
the same reason, it is undesirable to place two 
chandeliers in the same room. In still other in¬ 
stances the chandeliers would obstruct the view, 
and the lights would be in the line of sight. The 
best results, where reflectors are used, are obtained 
by placing the bulb lengthwise, or parallel with 
the reflector ; and by placing the lamp near to the 
surface of the reflector, the reflecting power is in¬ 
creased. When placing shades or globes over the 
lamps, allowance must be made in the amount of 
light, as a large quantity is absorbed, according to 
the shape, color, and proximity to the lamp. The 
surrounding, or prevailing color, of the walls, etc., 
must also be considered in the location and number 
of lamps. Where shadows are created, due to 
pilasters, etc. (where the light is evenly diffused 
there will be no shadows), to overcome the shadows, 
locate some lamps on the side of the pilaster, on 
which the shadow is thrown, or a circle of lights 
around the pilaster. This will remedy the defect. 

83. Lighting by electricity, on account of the 
absence of extreme heat, admits more artistic 
display, than does any other artificial illumination. 
Lamps can be located in recesses in the walls and 
ceilings, exposing only the lower half of the lamp 


118 


HOW TO WIRE BUILDINGS. 


bulb ; or, they may be concealed entirely and for 
their cover may have a finely finished piece of 
artistic glassware, etc. They can also be arranged 
to form geometrical figures, or placed in the centre 
of, or at the intersection of the figures forming the 
decorations. When placed in recesses and covered 
by glass, the distance between the lamp and glass 
cover should be such, that the shape of the carbon 
or lamp is not visible on or through the glass. 

In lighting theatres, concert rooms, lecture halls 
and similar places, in which there is some objective 
point, such as a stage or platform, the division, 
location and quantity of light should be such, that 
the proper effect at the objective point is secured, 
and that the light does not strain the eyes of the 
audience, and that the line of vision is not ob¬ 
structed by light between the objective point, and 
the audience. The lights should be so arranged 
that there is no reflection in the eyes. They should 
be located at the back of, or considerably above, 
the audience. 

When lighting show windows in stores, etc., 
locate the lamps as nearly as possible in the corner 
where the front intersects with the ceiling, pro¬ 
viding a tin shade or reflector having a white 
surface, and extending the same the entire length 
of the front, and placing the flat of the lamps 


HOW TO WIRE BUILDINGS. 


119 


parallel with the reflector, and quite close to it. 
The sidewalk should be darkened as much as 
possible to obtain good results. 

To illuminate stained and cathedral glass win¬ 
dows or ordinary-sized windows, form a reflector 
on each side of the window to be lighted, and place 
therein a sufficient number of lamps, so that a 
strong light will be obtained, and locate the same 
at a distance from the windows, so that the 
diffusion of light will be equal, and that the spots 
of light, or the carbons of the lamps, will not be 
discernible. Increase the dimensions of the win¬ 
dow, and the number of lamps and distance 
between same and the window, must be increased. 

84. One of the most difficult problems* in the art 
of lighting is the illumination of large paintings, 
etc. In fact, each subject is a separate problem, 
and must be treated accordingly. The treatment 
changes according to the size, shape, prevailing 
colors, if covered with glass or not, and the sur¬ 
roundings. The usual method is to place the lamps 
in a reflector, which is as long as the width of the 
picture, the reflector is shaped according to the 
size of the picture and the number of lights and dis¬ 
tance between the reflector and picture to be lighted 
must be such that the light is evenly diffused over 
the whole surface, and in such a manner that the 


120 


HOW TO WIRE BUILDINGS. 


picture can be viewed equally as well from either 
side, and so that the view will not be impaired by 
counter-reflection. 

If the painting is suspended from or fastened to 
the side wall, there should be no side lights located 
in its near vicinity ; and if placed on a stand 
or easel in the centre of the floor, care should be 
taken not to have any lights at the back of the 
painting, which tends to counteract the effect when 
viewing the picture. 

Paintings placed in a wooden box and covered 
with glass, are the most difficult of all, as the sur¬ 
rounding objects will be reflected in the glass. To 
overcome this requires an abundance of light, and 
the best results can only be decided by actual ex¬ 
periment. 

It is impossible to define rules governing all con¬ 
ditions of lighting. The object of this chapter has 
been to describe, in a general way, the methods 
usually employed, and the amount of light neces¬ 
sary for general illumination, and to suggest the 
method usually preferable in special cases. The 
style and methods to be employed can only be 
decided by experience. 


HOW TO WIRE BUILDINGS. 


121 


CHAPTER XIX. 


Distribution of Labor and Hints to Foremen. 

85. The amount of labor is governed by most of 
the conditions, as stated in previous chapters, but 
it can be so divided and directed, that the best 
results will be obtained, from an executive and 
financial standpoint. 

Let us assume a case in which the plans have 
been drawn in the drafting-room of the electric 
lighting company, and turned over to the foreman 
in charge, with instructions to install the work. 
Let us also assume (which is very often the case\ 
that the draftsman had not seen the building. The 
foreman, from these plans, estimates the amount of 
material required, and after ordering same, he 
should familiarize himself with the structure ; ob¬ 
serve which portions of the building are in a more 
advanced state of construction, and the manner in 
which the labor in the various branches of the 
building trades, is distributed. 

The plans instruct him as to the general location 
of wires, and the distribution of current, but he is 
responsible for the mechanical details, and waste 



122 


HOW TO WIRE BUILDINGS. 


(if any) of labor. Before the materials are received, 
he should select a safe place for same, and arrange 
to keep the ‘ ‘ lockup ’ ’ locked. 

When acquainted with the conditions of the 
building, he decides upon the number of men, that 
can be, to good advantage, employed on the work 
at any one time. The work should be started in 
that portion of the building, which is in a more 
advanced state of construction, so that, when once 
started, it can be completed without interruption 
or delay. It is advisable to keep the same men in 
the same part on the different floors of the build¬ 
ing, so that they will become familiar with the 
circuits in that section, as nearly all the office 
buildings, etc., from the second floor up, are the 
same. This will enable the man, after completing 
one floor, to do the work more quickly on each 
succeeding floor. It also demonstrates whether the 
amount of work is satisfactory, and when testing 
the result will show whether the man is careful or 
not. It is to the foreman’s interest to acquaint 
himself with the capabilities of the men under his 
supervision, so that he is better enabled to decide 
which to place on the more exacting and difficult 
work. The lengths of the circuits as shown on the 
plan should be conformed with, as nearly as possi¬ 
ble. The exact sizes of wires as noted on the plan 


HOW TO WIRE BUILDINGS. 


123 


should be used in all cases, but, should it become 
necessary to change the work, from the “ lay-out” 
on the plan, the company should be notified in 
season, so that instructions regarding the change 
may be given, and that the work will not be 
delayed, waiting for instructions. 

86. When the top or lamp circuits are nearly 
completed, provision should be made for testing 
them. It is also time to arrange for the cut-out 
boards which are to be set in the panel or closet. 
About this time, also, the question of running the 
mains and feeders should demand attention. 

The foreman should continually stroll through 
the building, watching the work already completed; 
the work under way ; observing the advancement 
in construction of the different portions of the 
building, and continually calculating as to the 
method of procedure on his own task, so that the 
wiring work will not delay the work in other 
branches, or vice versa. 

One familiar with the method of testing should 
be appointed to do this work, and his duty should 
not only be to test, but he should locate and repair 
faults, and 4 ‘ pick up ’ ’ and finish the innumerable 
“ odds and ends” which were left undone. One 
of the most important labor-saving methods, is to 
“lay-out” and work all the circuits, which run 


124 


HOW TO WIRE BUILDINGS. 


parallel to each other, at the same time, all of 
which connect to different cut-outs in the same box. 
It will obviate crosses, and to a great extent sim¬ 
plify matters. It is easier to trace the different 
circuits. 

The same plan is suggested when wires pass 
through walls, etc., provision can be made, at one 
time, for all. The most experienced and careful 
men should construct the cut-out and switchboards, 
and run the mains and feeder. 

87. The foreman should provide himself with a 
note-book, he will find it to be of service both to 
himself and employer. He should keep a record 
of, the date, amount, and kind of material; the 
result of each test; the changes (if any) in the 
wiring; additions or omissions in the lamps, 
switches, etc., the cause thereof ; extra work (if 
any) and by whose authority ; the general condi¬ 
tion of the plant when turned over to the customer; 
whether dynamo is belted direct to engine ; if so, 
whether engine does other work besides driving 
dynamo. If belted to pulley countershaft, note 
variations of speed, if any, and such other data as 
may be of interest to his employer, and obviate 
trouble for the future consumer. 


BOW TO WIRE BUILDINGS. 


125 


CHAPTER XX. 


Preliminary to Rules, Electrical Data, Etc. 

88. + is the sign of addition, and is called plus. 
Thus 2 -{- 6 indicates that 6 is to be added to 2 and 
is read 2 plus 6 or A + B, etc. 

— is the sign of subtraction, and is called minus. 
Thus 6 ■—•2 indicates that 2 is to be subtracted from 
6, and is read, 6 minus 2 or b — a, etc. 

X is the sign of multiplication, and is read, 
times, or multiplied by. Thus 2x6 indicates that 
2 is to be multiplied by 6, and is read 6 times 2, 
and, a x b denotes that multiplication of a x b. 

is the sign of division, and is read, divided by. 
Thus 6 •** 2 is an indication that 6 is to be divided 
by 2. 

Division is also indicated by writing the dividend 
above and the divisor below a short horizontal line 

6 

as in a fraction, thus The exponent of a quan¬ 
tity is the number which indicates how often the 
quantity is used as a factor. Thus, A 3 indicates 
that A is to be used as a factor three times, and A 3 
is the same as A x A x A. 



126 


HOW TO WIRE BUILDINGS. 


A* is read, “ A square” or “A second power,” 
A 3 is read “ A cube ” or “ A third power,” and, if 
A = 6, A’ = 6 X 6 = 36, or A 3 = 6 X 6 X 6 or 
6 X 6 = 36 X 6 = A = 218. 

The co-efficient is a number written before a 
quantity to show how many times the quantity is 
to be taken. Thus 3A would show that A is to be 
taken three times, and if A — 6, 3A = 6x3 = 
3A = 18. 

An algebraic expression, is the expression of a 
quantity, by means of algebraic symbols ; the 
symbols indicate the relation of quantities. 

A formula is a method of expressing in a simple 
and concise form, a rule or principle, and show the 
relation of one to another. Yolt is the unit of 
electrical pressure, (electromotive force) and is 
represented by E. 

Ampere is that current having an electric pres¬ 
sure of 1 volt which flows through a wire having a 
resistance of one ohm, and is represented by C. 

Ohm is that amount of resistance which, in a 
conductor, would limit the current, having a pres¬ 
sure of one volt, flowing through same, to one 
ampere, and is represented by It. 

According to Ohm’s law, the current in amperes 
is equal to the electromotive force in volts divided 

E 
R* 


by the resistance in ohms, thus, C = 



HOW TO WIRE BUILDINGS. 


127 


The electromotive force in volts is equal to the 
product of the current in amperes, and the resist¬ 
ance in ohms. Thus, E = C X R. The resistance 
in ohms is equal to the electromotive force in volts 

E 

divided by the current in amperes. Thus R = 

From these, can be ascertained the current in 
amperes, when the electromotive force in volts, and 
the resistance in ohms is known, and, 

The electromotive force in volts, when the current 
in amperes, and the resistance in ohms is known, 
and, 

The resistance in ohms, when the current in 
amperes, and the electromotive force in volts is 
known. 

Therefore in a machine, the resistance of which 
= .5 ohm and the electromotive force in volts = 

E = 100 volts 

100, the current m amperes equals ^ ^ — 

C = 200 amperes, and, C X R = E. 200 amperes 

E = 100 volts 

X .5 ohm = 100 volts, and, C = 200 amperes 
= .5 ohm. 


= R 


89. To ascertain the available current in amperes, 
not generated at the dynamo, but for consumption 
by or in the lamps, the resistance of the conductors 
must be added to the internal resistance of the 





128 


HOW TO WIRE BUILDINGS. 


dynamo, and if the resistance of the conduc¬ 
tors equals .0555 ohm, the available current 


E = 100 volts 



equals, r ^ ohm X R = .0555 


180 amperes. 

To ascertain the combined resistance of a number 
of lamps connected in multiple, divide the resist¬ 
ance of one lamp by the number of lamps. Thus, 
the combined resistance of 40 lamps connected in 
multiple, the resistance of one equaling 200 ohms, 


200 ohms = R of 1 lamp 
40 lamps 


= 5 ohms. 


would be 


To ascertain the combined resistance of a num¬ 
ber of lamps connected in series, multiply the 
resistance of one lamp, by the number of lamps. 
Thus, the combined resistance of 10 lamps con¬ 
nected in series, the resistance of one lamp equals 
200 ohms, would be, 

R of 1 lamp x number of lamps. Total resistance 
200 X 10 = 2000 ohms. 

To ascertain the combined resistance of a number 
of series of lamps, the series connected in multiple, 
divide the resistance of one series by the number 
of series. Thus, the combined resistance of 4 series 
connected in multiple, the resistance of one series, 
equal 2000 ohms, would be, 

2000 ohms = R of 1 series 


4 series 


= 500 ohms. 






HOW TO WIRE BUILDINGS. 


129 


Therefore, to ascertain the resistance required in 
the conductors, so that the loss in same equals, in 
the desired per cent., a certain proportion of the 
total resistance, it is necessary, if connected in 
multiple or series, to first ascertain the combined 
resistance of the lamps, and assuming, 20 lamps 
connected in multiple, the resistance of each lamp 
being 180 ohms, 5 per cent, loss of electrical energy 
to be allowed, in the conductors ; the distance 
being 350 feet from the dynamo, therefore, 

R of one lamp = 180 ohms = 9 = Tota i res i s t. of 
Number of lamps = 20 all lamps, 

and, 9 ohms representing 95 per cent, of the total 
resistance of the circuit at 5 per cent, loss, the total 

. 9 x 100 , , , 

resistance is, —-= 9,474 ohms = total resist¬ 


ance of lamp circuit. The length of the wire 
being 350 x 2 = 700 feet, and, .474 ohm is the 
resistance necessary to be contained in a wire 700 
feet in length, to supply current to 20 lamps located 
at a distance of 350 feet from the dynamo. If the 
lamps are connected in series, first ascertain the 
total resistance of the series, and the method of 
ascertaining the resistance of the conductor is sim¬ 
ilar to that, when the lamps are connected in mul¬ 
tiple, assuming the same number of lamps, per cent, 
of loss and distance from the dynamo, to be the 




130 


HOW TO WIKE BUILDINGS. 


same as in last example, but, that the lamps will 
be connected in series instead of multiple, there¬ 
fore the combined resistance of all the lamps equals, 
180 = R of one lamp 
20 = Number of lamps 
3600 = Total R of all lamps. 

5 per cent, being the desired amount of loss in the 
conductors, therefore 3600 ohms represents 95 per 
cent, of the total resistance of the lamp circuit, and, 


3600 X 100 
95 


= 3789.4 ohms = total R of lamp circuit, 


therefore, 3600 ohms = R of Lamps = 95 per cent, 
of circuit, and, 189.4 ohms = R of conductors = 5 
per cent, of circuit resistance. 


90. To ascertain the resistance of a one or a num¬ 
ber of corresponding wires, the method is similar 
to that for lamps. Mil. = .001 of an inch, and 
when made use of in relation to wiring, is the unit 
of length, when measuring the diameter, or cross- 
section of wires. Circular Mil is the unit of area 
employed in measuring the areas of cross-sections 
of wire. 

The diameter or cross-section of a wire is 
expressed in mils, and the area of cross-section in 
circular mils, therefore a wire, the diameter of 
which equals i inch — 250 mils, and to ascertain 
the circular mils it is necessary “ to square” the 




HOW TO WIRE BUILDINGS. 


131 


diameter, d 8 , 250 x 250 — 62500 circular mils. 
Foot-mil, equals a wire, the length of which 
equals one foot, and the diameter, one mil ; it is 
used in practice as a basis for computing the 
resistance of any given wire, and if the copper is 
commercially pure (usually 96 per cent, conduc¬ 
tivity), the resistance of same, at 75° Fahrenheit, 
equals 10.79 ohms. 

The resistance of a copper wire is equal to its 
length in feet, multiplied by the resistance of one 
foot-mil, 10.79, and divided by the circular mils, 
or “ the square ” of its diameter, therefore, 

d a or C j\T = and, assuming the length to be 

1500 feet and the circular mils = 10.381, the resist- 

_ 1500 X 10.79 

ance would equal —10 381 ~ 


— 1.559 ohms. 


The cross-section of a copper wire, in circular 
mils, is found by multiplying the resistance of a 
foot-mil (10.79) by its length (L) in feet, and divid¬ 
ing the result by its resistance (R) in ohms ; there¬ 
fore, 


10.79 X L 

R 


= d 8 or c. m., 


and, the resistance, and 


length of the wire being the same as in last 
example, the cross-section in circular mils would 


equal 


10.79 X 1500 
1.559 


= 10381 


= c. m. 






132 


HOW TO WIRE BUILDINGS. 


91. Having ascertained the resistance of the con¬ 
ductors, at the desired percentage of loss, for any 
given number of lamps, the cross-sections of same 
can be found, as shown in the previous example. 
To demonstrate: assuming 35 lamps, the R of one 
= 90 ohms, located at a distance of 160 feet from 
the dynamo, and 5 per cent, being the loss of 
energy desired in the conductors, 

90 ohms R of lamps , _ 

- 35 lamps - = 2.43 ohms = Total R of 

lamps. 2.43 ohms = 95 per cent, of total resistance 
of circuit, therefore the total resistance of circuit 


equals, 
cuit, and, 


2.43 X 100 


95 


= 2.558 ohms = Total R of cir- 
2.43 ohms = Total R of lamps, 
therefore, .128 ohms = Rof conductors. 
The distance being 160 feet, the total length of the 
wire equals 320 feet, and the cross-section in cir¬ 
cular mils, of a wire that length and resistance, is, 
10.79 x 320 

-- — 26.967 c. m. = No. 6 B. & S. gauge 


wire. 


92. The term “difference of potential” denotes 
that portion of the electromotive force which exists, 
at, or between, any two points in a circuit, and 
equals the electromotive force, (in a dynamo) at 
the point where the armature ‘ ‘ cuts ’ ’ the lines of 






HOW TO WIRE BUILDINGS. 


force, minus the amount lost in 
transmission, due to the resistance 
of the conductor : To illustrate : In 
an armature, there is created or 
generated a certain amount of 
current at a certain pressure ; the 
pressure decreases according to the 
resistance of the conductors ; there¬ 
fore, the electrical pressure at the 
brushes is less, due to the resistance 
of the armature coils, than in the 
armature, and less in the feeders, 
than at the brushes, etc. 

In the diagram A represents an 
armature of a dynamo, B represents 
the commutator or brushes, C rep¬ 
resents the feeder, D represents the 
main, and E represents the terminals 
at the lamp. At, or in A is “the 
electromotive force ; that is, the point 
at which the electrical pressure is the 
greatest. The pressure at B is less 
than that at A, due to the resistance 
of the armature coils, consequently 
its jiotency is less; that is, there ^ 
is at this point a “ difference of 
potential,” which is governed by the 








134 


HOW TO WIRE BUILDINGS. 


resistances of the conductors, and the pressure 
at B plus the amount lost in the armature coils, 
equals “the electromotive force.” The difference 
of potential in C the feeder, D the mains, and E at 
the lamp terminals is governed according to the 
same conditions. Assuming the electromotive force 
in A equals 125 volts, and the loss or drop of 
electrical pressure in the armature equals 1 per 
■cent., the “potential difference” at the brushes B 
would equal 123§ volts, and, if the loss in the feeder 
C equals 5 per cent, of that in B, the difference of 
potential in C would equal 117£ volts ; and, if in 
the main wire D, the loss is equal to 3 per cent, of 
the pressure in C, the difference of potential in same 
would equal 114 volts ; and, if the loss in the lamp 

wires, is equal to 2 per cent, of the pressure in D, 
the difference of potential at the lamp terminals 

would equal lllf volts. 

93. The term ‘ ‘ electromotive force, ’ ’ is generally 
used to denote the pressure at the highest pressure 
point; in all other parts of the circuit, the pressure 
is noted as the potential difference, or difference of 
potential. 


HOW TO WIRE BUILDINGS. 


135 


CHAPTER XXI. 


Rules for Ascertaining Required Sizes of Wire. 


94. The following rules enable us to determine 
the size of wire necessary, for any number of lamps, 
at any distance (see safe-carrying capacity), and at 
any desired loss, expressed in circular mils : 

Rule 1 . Multiply the resistance of one foot-mil 
by twice the distance, and by the number of lamps, 
and by 100, minus the per cent, loss, and divide 
the result by the resistance of one lamp multiplied 
by the percentage of loss. The loss should be 
expressed as a whole number. Thus, 

Rof 1 Ft.-mil X 2 X D X No. of lamps 100 — loss 
R of one lamp X % loss 

= C. mils. 

Example : 80 lamps, located at a distance of 140 
feet, R of Lamp = 200 ohms, to determine the size 
of wire at 5 per cent, loss : 

Foot-mil = 10.79 ohms. 


10.79 X 2 X 140 X 80 100—5 

200 X 5 

241696 95 

X 


22961120 


200 ~ 5 “ 

B. & S. G. wire. 


= 22961 cir. mils = No. 6 


1000 











186 


HOW TO WIRE BUILDINGS. 


Rule 2. To determine the size of wire, the loss 
or “drop” expressed in volts, multiply the resist¬ 
ance of one foot-mil, by twice the distance, and by 
the number of amperes, and divide the result by 
the number of volts to be “ lost,” thus, 

R of 1 Ft.-mil x 2 X D X amperes 
-V olts ' drop. -= c - mlls - 

Example : 185 100-volt lamps, located at a dis¬ 

tance of 260 feet. ■ 

The resistance of each lamp = 140 ohms. Drop 
= 3 volts. 

It is necessary to find the amount of current, in 
amperes, required for each lamp, and according to 

E 

Ohm’s law, C = therefore, the current required 

for, or consumed by each lamp equals, 

Volts 100 5 

■oEiii5T40' = T ampere ’ and ’ 

X 185 = 132.14 amperes, and, 

10.79 x 2 X 260 x 132.14 
-«- = 247123 c. mils. 


95. Where the conditions of the lamps do not 
change, that is, where the wiring is installed for 
connection, and use of the same kind of lamps, 
continuously, it will be found handy to have “a 
-constant ” already calculated for the different losses, 








HOW TO WIRE BUILDINGS. 


137 


■and it is found by multiplying the resistance of one 

foot-mil, by two, and the result, by 100 minus the 

desired loss, and divide the result by the resistance 

of one lamp multiplied by the loss. The loss to be 

expressed in whole numbers, thus, 

Rof Ft.-mil x 2 100—loss 

R of lamp- x loss ~ = constant ’ and, 

assuming the R of lamp = 200 ohms and the loss 

— 5 percent., the constant would be, 


10.79 x 2 100 — 5 

200 x 5 “ 

21.58 95 2050 

9()() - x -g- — = constant 2.05 = and, to 

ascertain the size of wire, expressed in circular mils, 
for a given number of lamps, a certain distance, at 
any desired loss, multiply the number of lamps, by 
the distance in feet, and the result, by the constant 
for the loss desired ; thus, 

No. lamps X distance x constant = cir. mils. 
Example : The resistance of lamp, and per cent, 
loss, as in previous example ; determine the size of 
wire required, for 175 lamps, at a distance of 135 
feet. 175 X 135 X 2.05 = cir. mils = 48431 = No. 
3 B. & S. G. wire. 


96. The cross-section of wire should be such, 
that it will conduct the current without becoming 
heated to the point where the temperature is greatly 










138 


HOW TO WIRE BUILDINGS. 


in excess of that of the surrounding air. The 
evidence of this condition can be got by grasping 
the wire with the bare hand. All wires become 
heated when a current of electricity is passed 
through them ; and by increasing the amount, in 
amperes, in any given wire, the heat is increased. 

According to the rules for wiring, the result is 
the same in circular mils, for 100 lights one foot as 
for one light 100 feet. It is easily understood that 
this is not correct, therefore care must be taken, in 
short distances to provide a sufficiently large wire, 
in diameter, so that same will not become unduly 
heated. The accompanying table is a safe practical 
guide, and when figuring wire, should the circular 
mils, per ampere, be less than mentioned in the 
table, it is advisable to determine the sizes required 
allowing per ampere, the number as stated therein, 
rather than by the rules. Allowance in circular 
mils per ampere, being the safe carrying capacity. 


HOW TO WIRE BUILDINGS. 


139 


SAFE CARRYING CAPACITY. 


(as ordered by the board of fire underwriters.) 


Brown & Sharpe. 

Birmingham. 

Edison 

Standard. 

Gauge No. 

0000. . 

Amperes. 

. . .175 

Gauge No. 

0000.. 

Amperes. 

. ..175 

Gauge No 

200. . 

Amperes. 

....175 

000. . 

...145 

000. . 

i—i 

Ox 

o 

180. . 

....160 

00. . 

. . . 120 

o 

o 

...130 

140. . 

.... 135 

0. . 

. ..100 

0. . 

. . . 110 

110. . 

.... 110 

1 . . 

. . . 95 

1 . . 

. . . 95 

90. . 

.... 95 

2. . 

. . . 70 

2. . 

. . . 85 

80. . 

.... 85 

3. . 

. . . 60 

3. . 


65. 


4. . 

. . . 50 

4. . 


55 . 

.... 65 

5 . . 

. . . 45 

5 . . 

... 60 

50. 

.... 60 

6. . 


6. . 


40. 


7. . 

. . . 30 

7. . 

. . . 45 

30. 

.... 40 

8. . 

. . . 25 

8. . 

... 35 

25 . 

.... 35 

10. . 

. . . 20 

10. . 

... 30 

20. 

.... 30 

12. . 

. , . 15 

12. . 

. . . 20 

12. 

. 20 

14. . 

. . . 10 

14. . 


8. 


16. . 

. . . 5 

16. . 

. . . 10 

5. 

. . . . 10 

18. . 

... 3 

18. . 

... 5 

3. 




20. . 

... 3 

2. 

. 3 











































































140 


HOW TO WIRE BUILDINGS. 


CHAPTER XXII. 


E N E R G Y —P O W E R . 

97. The energy which is developed in a circuit, 
when a current of one ampere liows through a 
conductor whose resistance is one ohm, is termed a 
watt. The watt is the electrical unit of power, 

1 

and equals horse-power, or, liorse-power = 

33,000 foot-lbs., that is, a liorse-power equals that 
power which will raise 33,000 lbs. a distance of one 

foot, in one minute of time, and-H. P. = 44.25 

746 

foot-lbs. per minute. The number of watts developed 
in a circuit is determined by multiplying the am¬ 
peres by the volts, 

Amperes X volts, or C x E = watts, or C 2 x R 
= watts. 

And if expressed in the terms of the mechanical 
unit (horse-power) 

C E C 2 R 

746 or 746 _ = horse-power. 

If expressed in foot-pounds, C X E x 44.25, or, 
C a X R X 44.25 = foot-lbs. 







HOW TO WIRE BUILDINGS. 


141 


Example: Determine the electrical energy, ex¬ 
pressed in liorse-power, developed in a dynamo, 
connected to 750 16-c. p. lamps, each lamp requiring 
i ampere of current at a pressure of 100 volts. The 
loss in the wires equals 5 per cent. 

750 lamps X ^-ampere = 375 amperes, 

C x E = watts 
and, 375 amperes x 100 volts = watts = 37500 and, 
watts X 44.25 = foot-lbs. 

37500 x 44.25 = 1658375 = the energy, expressed 
in foot-lbs., expended in the lamps, and represents 
95 per cent, of the total as the remaining 5 per cent, 
is expended or lost in the conductors, therefore 
1658375 = 95 per cent, of total energy, and 

87284 = 5 “ “ “ “ 

1745659 = Total energy, expressed in foot-lbs., 
expended in the lamps and conductors, and foot¬ 
pounds, divided by 33000 equals horse-power, there¬ 
fore, 1745659 -*■ 33000 = 53 horse-power. 

To lind the actual horse-power expended at the 
pulley of the dynamo, assuming the efficiency of 
the dynamo to be at 90 per cent., and according to 
the last example, 1745659 foot-pounds were ex¬ 
pended in the lamps and conductors, therefore, the 
efficiency of the dynamo being 90 per cent., it 
represents only 90 per cent, of the power expended 



142 


HOW TO WIRE BUILDINGS. 


at the pulley of dynamo, and as 1745659 = 90 % y 

and, 193962 = 10 % 

1939621 = Total 

energy in foot-pounds ; therefore, 1939621 33000 

= 58.777 = total amount of energy in horse-power 
expended at the pulley of the dynamo, and if 
belted to engine, 10 per cent, being lost in the 
transmission of power, then 

58.777h. p. = 90%, and 
6.53 h. p. = 10 % loss 
65.307 h. p. represents the amount of 
horse-power at the pulley of the engine. 

In the first example it was shown that 87.284 foot 
pounds were expended in the conductors due to 
their resistance, which equals, 87284 33000 = 

2.645 or 2f horse-power, and the cost, in dollars and 
cents, equals 2f X lbs. of coal per h. p. hour x 
cost of lbs. of coal 

= $ and cts. 

This is but another example, of the importance 
of carefully considering the question of 4 4 loss ’ ’ in 
conductors. 




HOW TO WIRE BUILDINGS. 


143 


CHAPTER XXIII. 


Dynamos and Motors. 

98. In setting, connecting, or running a dynamo, 
or motor, unless you are familiar with all its parts, 
method of winding, and connections, it is very 
important that a blue print or diagram, showing 
the different parts, and method of connections, etc., 
be procured. 

99. The machine should be located in a clean, dry 
place, and where the temperature is not high ; it 
should be isolated, as much as possible, from 
other machinery, especially in saw mills, machine 
shops, etc., where more or less dust, or metal filings 
are flying, but at the same time it should be access¬ 
ible. If the machine is set on an ordinary floor, 
provision should be made against vibration. The 
base frame should be treated to a coating of hot 
paraffine, for closing the pores, and a thick coating 
of shellac. In putting the machine together, care 
must be taken to have all the parts clean, and all 
connections, bearings, etc., must be put together so 
that the “ fit ” will be perfect. All parts, especially 
the armature and magnets, must be handled with 



144 


IIOW TO WIRE BUILDINGS. 


the utmost care, and must not be handled any more 
than is necessary. 

100. Before starting, adjust and test the brushes 
for tension. See that the main connections in the 
circuit are open ; examine all connections ; provide 
each cup or automatic lubricator, with sufficient oil, 
and see that the feed is in proper working order. 

In a shunt-wound machine, when up to speed, 
the brushes can be dropped on the commutator, and 
if hand regulator is used, the resistance should be 
thrown out of the field, until the needle on the 
indicator is at the x>oint showing the required 
pressure. The lamp at the head of the dynamo is 
generally a guide. 

101. It is preferable to run the machine, for an 
hour or so, at full speed, without any current gen¬ 
erated, so that the bearings can be worked smooth, 
and tested before the machine is put to actual 
work, and in case the bearings become heated, the 
defect must be remedied. 

When a shunt-wound machine is to be connected 
in circuit, in multiple with another, it should be 
brought up to speed, and the field resistance grad¬ 
ually thrown out, until the pilot lamp, at the head 
of the machine, is practically at its full normal 
candle-power. The machine can then be connected 
in the circuit, and by watching the pressure indi- 


HOW TO WIRE BUILDINGS. 


145 


cator, and throwing out the held resistance, the 
machine will gradually perform its share of the 
work. When two or more shunt-wound machines 
are in multiple, all held and line connections should 
be traced and examined before starting. 

102. In a compound-wound machine, the magnets 
are wound similarly to those of the ordinary shunt- 
wound machines, but have, in addition, extra coils 
in series, and arranged so that according to the 
number of lamps in use, each receives a certain 
amount of the current. A change in the number of 
lamps, connected in the circuit, will cause an 
increase of current in one, and a proportionate 
decrease in the other, so that the pressure is kept 
at a constant point, the series coils acting as an 
automatic regulator. 

Any number of machines can be run in multiple, 
provided the pressure or electromotive force of 
all corresponds. Should the pressure on one 
be less than that of the others, it is liable to 
be run by them as a motor. With dynamos 
connected in multiple, the pressure of all is equal 
to that of any one machine, but the current, in 
amperes, is increased according to the capacity 
of all, for example : Three machines having a 
capacity of 100, 50 and 25 amperes, respectively, 
the pressure of each equals 125 volts, the com- 



146 


HOW TO WIRE BUILDINGS. 


bined* output would equal 175 amperes at a 
pressure of 125 volts. 

103. In stopping the machine, if running singly, 
slow the speed of the engine, which reduces the 
pressure in the dynamo ; throw the resistance coils 
in the held circuit, if hand regulator is used ; and 
just before the engine is stopped, break the line 
connection, and lift the brushes. 

If the machine is connected in multiple with 
another, in order to stop or disconnect it from the 
circuit, regulate its amount of work so that it will 
be as small as possible, then break the line connec¬ 
tion ; but the held must correspond in strength to 
that in the other machines, so that it may not be 
run as a motor. 

This same method applies to machines connected 
to three-wire circuits, and also to compound-wound 
machines, when the equalizer is kept closed. 

104. Two dynamos connected to the three-wire 
system, are practically similar to two dynamos 
connected in multiple ; the positive of one, and the 
negative of the other machine, are connected to the 
middle or neutral wire of the circuit. The other 
pole of each machine forms the positive and nega¬ 
tive pole, respectively. 

In starting the machines, each should be started 
separately, and not at the same time. When one 


HOW TO WIRE BUILDINGS. 


147 


machine is connected and running, the second 
machine, when up to the required pressure, can be 
connected in the circuit. The method of stopping, 
as stated, is the same as if in ordinary multiple. 

105. In connecting machines in series, the positive 
pole of one connects with the negative pole of the 
next machine ; the current in amperes remains con¬ 
stant, but the pressure in volts increases with every 
additional machine ; the voltage of the machines 
need not be the same, but the current capacity of 
each must correspond with the others. 

In constant current machines, when starting, it 
is only necessarv to examine the connections, and 
have the circuit completed. The line or circuit 
should never be broken while running, as the field 
may “burn out,” or if broken at the brushes, an 
arc will be created, that will burn the commutator. 
In stopping simply slow the speed, if possible, 
until the armature stops revolving. 

If connected to shafting, or arranged so that 
speed cannot be stopped, then open the field circuit, 
but under no consideration, must the line be broken. 

The method of starting and stopping is the 
same for a single series machine, or a number of 
them. 

106. In setting up motors, the same care and 
attention must be given to all the parts and bear- 


148 


HOW TO WIRE BUILDINGS. 


ing, as to dynamos. A bine print or diagram, 
showing the method of connecting the motor and 
the starting or regulating box, and directions for 
running same, should be provided. 

In a series-wound motor, which is connected in 
an “arc light” circuit, the connections are simple. 
The motor is “ cut-in” the circuit in the same 
manner as an arc lamp, a switch is provided and 
connected in the line (arc light hand switch), which 
is used for starting or stopping the motor ; as in a 
series dynamo, the line must never be broken, or, 
the brushes must never be raised from the commu¬ 
tator. 

Constant potential motors are wound in a manner 
similar to the ordinary shunt-wound dynamo, and 
with each motor is provided a starting box, com¬ 
posed of a number of coils, and constructed 
somewhat similar to a resistance box, used for 
regulating the held of shunt-wound dynamos. The 
wire forming one side of the circuit is connected to 
the post of the cross-bar, on the face-board of the 
starting box, and the cross-bar through a coil in 
the box forms the connection between one of the 
held wires and the line. The cross-bar also forms, 
through a number of coils, the connection between 
the line and one of the brush wires. The line 
should always be provided with a double-pole cut- 


HOW TO WIRE BUILDINGS. 


149 


out and switch. To start the motor, close the 
switch in the line, and turn the connecting strip or 
cross-bar on the starting box, until it rests on the 
first connecting plate on each side. Allow it to 
rest on these for an instant, so that the fields will 
be charged. As the armature begins to turn, move 
the cross-bar from plate to plate, which throws out 
the resistance, and the motor will then have attained 
its full speed. The movable bar on the starting 
box must not be allowed to rest on any of the con¬ 
necting plates (with the exception of the first, for 
only a moment), but must be steadily moved to the 
last plate. This box is not to be used as a regu¬ 
lator, but is only for use when starting or stopifing, 
as the capacity of the wires is not sufficient to carry 
the current for even a short space of time. 

107. A speed regulator is constructed in a some¬ 
what similar manner to the starting box, and the 
cross-section of the wires is such, that they can 
carry the current without unduly heating. In 
stopping, turn the handle, at the starting box, in 
the opposite direction to that when starting, and 
when it is brought to the last connection, the circuit 
is broken, although it is more preferable to allow 
the bar to rest on the connecting plate, next to the 
last, and break the connection at the line switch. 


150 


HOW TO WIRE BUILDINGS. 


CHAPTER XXIV. 


Pulleys. 

108. In all machines, whether a dynamo or motor, 
the pulley is furnished with the machine. The 
width of face and diameter, have been determined 
by the maker. The size of the pulley on the 
dynamo has been determined, according to the 
speed and power required to drive it when at its 
full rated capacity. The pulley on the motor is 
determined by the rated speed at which the motor 
is to run, and its rated liorse-power. 

The pulleys on the machines should not be altered, 
or pulleys of other dimensions used ; and where 
conditions exist, which necessitate a change in size, 
the maker should be notified. He will either make 
the change, or forward instructions regarding the 
matter. 

In dynamos driven by an engine, the dimensions 
of the driving wheel is usually determined by the 
electric lighting company or the maker of the 
engine. The diameter is determined by the number 
of revolutions per minute of the engine shaft, the 
revolutions, per minute, necessary for the capacity 



HOW TO WIRE BUILDINGS. 


151 


of the dynamo, and the diameter of the dynamo 
pulley. When the dynamo is belted to a pulley on 
a countershaft, the shaft must be considered as the 
shaft on the engine. 

The face or width of a pulley is a trifle larger 
than the width of the belt. 


109. To ascertain the required diameter of the 
driving pulley: Multiply the diameter of the 
dynamo pulley by the number of revolutions per 

T 

minute required, and divide the product, by the 
number of revolutions per minute, of the shaft, 

Dia. of Dynamo Pulley X required speed 
Revolutions of shaft, per minute, 

diameter of driving pulley. 

Example : To determine the diameter of pulley 
to drive a dynamo, having a pulley 10 inches in 
diameter, and requiring 1,500 revolutions per 
minute. The revolutions of the shaft per minute 
= 225, therefore, 


10 x 1500 
225 


66f inches = diameter of driving 


pulley. 

In motors, the dimensions of the pulley being 
already determined by the maker, the speed at 
which the machinery or shaft is driven by the 
motor, depends on the speed of the motor, and the 
diameter of the pulleys. The diameter of the 




152 


HOW TO WIRE BUILDINGS. 


pulley on the machine or shaft to be driven at a 
certain speed, depends upon the speed and diameter 
of the motor pulley. 

To ascertain the diameter of the driven pulley for 
any desired speed or number of revolutions per 
minute, multiply the revolutions per minute, of the 
motor pulley, by its diameter, and divide the 
product, by the number of revolutions, desired for 
the driven pulley. Thus, 

Speed of motor x diameter of motor pulley 
Desired number of revolutions for driven pulley — 

Diameter, in inches, of driven pulley. 

Example : To determine the diameter of a pulley 
requiring 200 revolutions per minute, the rated 
speed of the motor being 1,200 revolutions per 
minute, and the diameter of pulley on same equals 
9 inches, therefore, 


1200 X 9 
200 


54 inches = diameter of driven 


pulley. 

By these methods, the driving or driven pulley 
can be ascertained. 




HOW TO WIRE BUILDINGS. 


153 


CHAPTER XXY. 


Belting. 

110. All belts and lacing should be the best pro¬ 
curable. The belt should be placed on the pulley, 
with the smooth side in contact. If the belt tends 
to run to either edge of the pulley, move the 
dynamo or motor in that direction, until the belt 
remains in the centre. 

Do not skimp on the width or length of the belt, 
it being desirable to have it a trifle larger than is 
actually necessary rather than too small. 

In dynamos or motors, the width of the belt is 
governed by the width of the face of the pulley on 
same. The pulley is usually one inch wider than 
the belt. 

Belts driven horizontally give better satisfaction 
than those driven in a vertical position, as the arc 
of contact is increased in horizontal driving. 

111. Avoid excessive strain, and protect the belts 
from dirt, exposure, extreme dampness or extreme 
dryness. Applying neats-foot oil occasionally will 
keej3 the belt soft and pliable. 



154 


HOW TO WIRE BUILDINGS. 


112. A single belt traveling 1,000 feet per minute 
transmits one horse-power, provided the arc of 
contact equals 180°, or if it binds or touches one- 
half the surface of the circumference of the pulley. 

Rule for ascertaining the width of belt for any 
desired liorse-power: 

Width of belt x speed of belt in ft. x arc of contact 

Tbbo “ ' 

= h. p. 



HOW TO WIRE BUILDINGS. 


155 


CHAPTER XXVI. 


Engines. 

113. Although wiremen are not expected to be 
steam engineers, yet there are times when a knowl¬ 
edge of starting and stopping an engine may be 
very serviceable, as in the case of sudden sickness 
of the engineer in charge of plant, and where illum¬ 
ination is imperatively required. 

The engines mostly used for driving dynamos are 
of the horizontal, high-speed type. The steam 
pressure is usually 80 pounds to the square inch, 
to obtain the required speed of revolution. 

114. Before starting an engine, supply all the oil 
cups and 44 self ’ ’ -lubricators with a sufficient amount 
of oil, and see that the 44 feed 11 is properly adjusted. 
Open the rear ports, or drips, usually located in 
the back of and under the cylinder, to allow any 
condensed water to run out. Set the engine on its 
44 centre ” and then slightly open the steam valve, 
to heat the piston and cylinder. When one side is 
44 warmed up ” turn the pulley over to the opposite 
4 4 centre ’ ’ and heat the opposite part of the cylin¬ 
der, piston, etc. When the engine is heated, and 



156 


HOW TO WIRE BUILDINGS. 


the steam gauge indicates the pressure required, 
open fully the exhaust valve, close the rear j>orts, 
or drip cocks, and slightly open the steam valve. 
Turn the driving pulley in the proper direction, 
and when the engine is running slowly, note whether 
it is running smoothly. Keep opening the steam 
valve gradually, until it is fully opened, and the 
engine is running at full speed. Attention can then 
be given to the starting of the dynamo. 

115. While the engine is running, observe from 
time to time the amount of pressure indicated at 
the gauge, and watch the lubricators, etc. 

If any loud noise or pounding be heard in the 
engine, shut down at once, as water may from some 
reason have been carried into the cylinder, and if 
the engine were kept running, the result would be 
that the cvlinder-liead would be blown out, and the 
engine be ruined. 

To stop the engine, gradually close the steam 
valve, be careful that the engine is not stopped too 
sudden. Slowly bring the driving wheel to a stand¬ 
still. When the engine is stopped, close the feed 
of the lubricators, clean all parts of the engine, and 
cover it with the cloth provided for the purpose. 

116. Under no consideration must it be attempted 
to repair any part or parts of the engine, and it is 


HOW TO WIRE BUILDINGS. 


157 


suggested that, unless the engine is in good order, 
and the case urgent, the wireman should not in any 
manner handle the engine, unless he is an expe¬ 
rienced engineer. 


158 


HOW TO WIRE BUILDINGS. 


CHAPTER XXVII. 


Conclusion. 

117. Wiremen should familiarize themselves with 
the different kinds and qualities of material, so that 
they may be enabled to get the best of any partic¬ 
ular kind. In the matter of appliances, they should 
know just what is the best for the special purpose. 
Xew appliances, etc., are being placed on the 
market continually, and unless a knowledge of the 
same is acquired, antiquated, obsolete and inferior 
materials and devices will be used to the disad¬ 
vantage of the customer. The writer would advise 
all wiremen to subscribe to some journal devoted 
exclusively to the discussion and publication of 
electrical engineering work. Hardly a week goes 
by but what some one or more articles treat on new 
methods of wiring and kindred work. It is very 
instructive and at the same time interesting. We 
are also enabled, through the same source to obtain 
information on the various appliances, and where 
the same can be purchased. We are better able to 
keep in line with all improvements in all branches ; 
as an instructor, the press has no equal, and it has 



HOW TO WIRE BUILDINGS. 


159 


the advantage, moreover, of continually devising 
new ways by which the wireman may get greater 
profit from his experience and rise to larger 
responsibilities and opportunities. 


160 


HOW TO WIRE BUILDINGS. 


Tables of Different Gauges, with their Respective. 

Diameters and Areas. 


Browne & Sharpe. 

Birmingham. 

No. of 

Diameter 

Area in 

No. of 

Diameter 

Area in 

Gauge. 

in Mils. 

CM = d 2 . 

Gauge. 

in Mils. 

C M = d 2 . 

4-0 

.4600 

211600 

4-0 

.454 

206116 




CO 

1 

o 

.425 

180625 

3-0 

.4096 

167805 




2-0 

.3648 

133079 

2-0 

.380 

144400 




0 

.340 

115600 

0 

.3249 

105592 







1 

.300 

90000 

1 

.2893 

83694 

2 

.284 

80656 

2 

.2576 

66373 

3 

.259 

67081 

3 

.2294 

52634 

4 

.238 

56644 




5 

.220 

48400 

4 

.2043 

41742 

6 

.203 

41209 

5 

.1819 

33102 

7 

.180 

32400 

6 

.162 

26244 

8 

.165 

57225 

hr 

l 

.1443 

20822 

9 

.148 

21904 

8 

.1285 

16512 

10 

.134 

17956 

9 

.1184 

13110 

11 

.120 

14400 

10 

.1019 

10381 

12 

.109 

11881 

11 

.0907 

8226 

13 

.095 

9025 

12 

.0808 

6528 

14 

.083 

6889 

13 

.072 

5184 

15 

.072 

5184 

14 

.0641 

4110 

16 

.065 

4225 

15 

.0571 

3260 

17 

.058 

3364 

16 

.0508 

2581 

18 

.049 

2401 

17 

.0452 

2044 

19 

.042 

1764 

18 

.0403 

1624 




19 

.0359 

1253 

20 

.035 

1225 

20 

.032 

1024 

21 

.032 

1024 

21 

.0285 

820 

22 

.028 

784 

22 

.0253 

626 

23 

.025 

625 

23 

.0226 

510 

24 

.022 

484 

24 

.0201 

404 

25 

.020 

400 

25 

.0179 

320 

26 

.018 

324 






















HOW TO WIRE BUILDINGS. 161 


WEIGHT OF COPPER WIRE. 


No. 

One Thousand Feet. 

One Mile. 

B. & S. 

B. W. G. 

B. & S. 

B. W. G. 

0000 

639.33 

622.36 

3375 

3286 

000 

507.01 

546.22 

2677 

2884 

00 

402.09 

436.56 

2123 

2305 

0 

319.04 

349.63 

1684 

1846 

1 

252.88 

272.17 

1335 

1437 

2 

200.54 

243.76 

1058 

1287 

3 

159.03 

202.84 

839 

1071 

4 

126.12 

171.21 

665 

904 

5 

100.01 

146.40 

528 

773 

6 

79.32 

124.43 

418 

657 

H 

i 

62.90 

97.92 

332 

547 

8 

49.88 

82.39 

263 

435 

9 

39.56 

66.29 

209 

350 

10 

31.37 

54.36 

166 

287 

, 11 

24.88 

43.56 

131 

230 

12 

19.73 

35.98 

104 

190 

13 

15.65 

27.27 

83 

144 

14 

12.41 

20.83 

65 

110 

15 

9.84 

15.72 

52 

83 

16 

7.81 

12.88 

41 

68 

17 

6.19 

10.18 

33 

53 f 

18 

4.92 

7.20 

26 

38 

19 

3.93 

5.30 

20 f 

28 

20 

3.09 

3.60 

16 4 

19 * 

21 

2.45 

3.09 

13 

16 * 

22 

1.94 

2.37 

10 * 

12 * 

23 

1.54 

1.94 

H 

ioi 

24 

1.22 

1.47 

6 * 

Vi 

25 

.97 

1.22 


6 -i 

26 

.77 

. 95 

4 

5 

27 

.61 

.75 

3 i 

4 

28 

.48 

. 61 | 


Ql 

29 

.38 

.50 

2 

2 § 

30 

.30 

.42 

If 























162 


HOW TO WIRE BUILDINGS 


Table Showing Fractions of an Inch Reduced to 

Decimal Equivalents. 


A . 




.015625 

• • • •inr * • 



u 

.031250 

3 



u 

.046875 

6 4 

• • A • • 


u 

.062500 

A . 


u 

.078125 

3 



a 

.093750 

* ’ ' * 3 2 ’ * 

A . 



u 

.109375 


1 

i( 

.125000 

A . 



u 

.140625 

5 

* * * •32 * • 



u 

.156250 

A . 



a 

.171875 

3 


u 

.187500 

.203125 

.218750 

1 3 

* * 1 6 * * 


u 

0 4 

• • • 'A' • 



u 

if. 



« 

.234375 



1 

a 

.250000 

.265625 

it . 



a 

_9_ 



a 

.281250 

.296875 

’ ’ * ' 32 * * 

. 



a 

6 4 

. .A - • 


a 

.312500 

.328125 

ii . 

16 


a 

11 



a 

.343750 

.359375 

.375000 

.390625 

.406250 

.... 3 2 . . 

2 3 



a 

6 4 


3 

a 

14. 



a 

6 4 

• • •* 32 • * 



a 

n . 



u 

.421875 




u 

.437500 

14. 



u 

.453125 

.468750 

6 4 

... .j|-.. 



a 

n . 



a 

.484375 



1 

a 

.500000 











































DIMENSIONS, WEIGHT AND RESISTANCE OF BARE COPPER WIRE—AM. GAUGE 


Gauge 

No. 

Diameter in 
Mils. 


Weight. 

Length- 

-Feet. 

Resistance— Ohms. 

Gauge 

oOCi' tircft in , 
Circular Mils. 

Lbs. per Foot. 

Lbs. per Ohm. 

Per Lb. 

Per Ohm. 

Per Foot. 

Per Lb. 

No. 

0000 

000 

00 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 
86 
37 
88 

39 

40 

.46 

.40964 
.3648 
.32486 
.2893 
.25763 
.22942 
.20431 
.18194 
.16202 
.14428 
.12849 
.11443 
.10189 
.090742 
.080808 
.071961 
.064084 
.057068 
.05<'82 
.045257 
.040303 
.03589 
.031961 
.028462 
.025347 
.022571 
.0201 
.0179 
.01594 
.014195 
.012641 
.011257 
.010025 
.008928 
.00795 
.00708 
.006304 
.005614 
.005 
.004453 
.003965 
.002531 
.003144 

211600. 

167805. 

133079. 

105534. 

83694. 

66373. 

52634. 

41743. 

33102. 

26251. 

20817. 

16510. 

13094. 

10382. 

8234. 

6530. 

5178. 

4107. 

3257. 

2583. 

2048. 

1624. 

1288. 

1021. 

810. 

642. 

509. 

404. 

320. 

254. 

201. 

159.8 

126.7 

100.5 

79.7 
63. 
50.1 
39.74 
31.5 
25. 

19.8 
15.72 
12.47 

9.88 

.640525 
.507955 
.40284 
.319457 
.253348 
.200915 
.159325 
.126357 
.10022 
.0794616 
.0630134 
.0499757 
.039637 
.0314256 
.024925 
.0197665 
.0156753 
.0124314 
.0098584 
.0078179 
.0062 
.004917 
.0038991 
.0030922 
.0024522 
.0019448 
.0015421 
.001223 
.0009699 
.0007691 
.0006099 
.0004837 
.0003836 
.0003042 
.0002413 
.0001913 
.0001517 
.0001203 
.0000954 
.00007568 
.00006003 
.00004759 
.00003774 
.00002992 

13129.29 

8256.95 

5193.13 

3265.84 

2054.015 

1291.80 

812.709 

522.839 

321.309 

202.062 

127.07 

79.9258 

50.2886 

31.6036 

19.882 

12.5034 

7.86319 

4.51033 

3.11015 

1.95501 

1.23013 

.773677 

.486524 

.305979 

.192429 

.121037 

.076105 

.0478624 

.0301038 

.0168719 

.0119056 

.0074748 

.0047087 

.00296174 

.0018306 

.00117133 

.000733789 

.0004631 

.000291272 

.000183269 

.000115298 

.0000724741 

.0000455828 

.0000369803 

1.56122 

1.9687 

2.4824 

3.1303 

3 91714 
4.97722 
6.2765 
7.9141 

9 97983 
12.5847 
15.8696 
20.0097 
25.229 
31.8212 

40 1202 
50.5906 

63 7948 
80.4415 
101.4365 
127.12 
161.29 
203.374 
256.468 
323 399 
407.815 
514.193 
648.452 
817.688 
1031.038 
1300.180 
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12891.37 

10223.08 

8107.49 

6429.58 

5098.61 
4043.6 

3206.61 
2542.89 
2015.51 
1599.3 
1268,44 
1055.66 

797.649 

632.555 

501.63 

397.822 

315.482 

250.184 

198.409 

157.35 

124.777 

98.9533 

78.473 

62.236 

49.3504 

39.1365 

31.0381 

24.6131 

19.5191 

15.4793 

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9.7355 

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13.13974 

20.89323 

33.2184 

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212.373 

337.639 

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1 


^pHE India Rubber = 

AND GUTTA=PERCHA 
- — Insulating Company. 


W. M. HABIRSHAW, General Manager, 
315 MADISON AVENUE, 

NEW YORK CITY, U. S. A. 




M AN UFAcr 0 


HABIRSHAW 




*'*£8 AND c 









“THE NATION’S CHOICE.” 



GRIMSHAW 
White Cere Wires. 


GRIMSHAW TAPES. 

VULCA ELECTRICAL WIRE DUCTS. 
RAVEN CORE WIRES. 
COMPETITION LINE WIRES. 


SOLE MANUFACTURERS, 

New York Insulated Wire Co., 

15 Cortlandt St., New York. 

BRANCHES:—Boston, Chicago, San Francisco. 


Foster on Central Station Management 

and Finance. 

PROFUSELY ILLUSTRATED WITH SPECIAL FORMS, Etc. 


This is what President Huntley , of the National Electric Light Association , 
said regarding it in his inaugural speech : 

“A most valuable series of articles on Central Station Management and 
Finance, by H. A. Foster. I trust every Electric Eight Man will read it. 
The subject is admirably treated from a practical standpoint, and it is impos¬ 
sible not to derive good from the many hints and suggestions, while the many 
forms and blanks may be adopted with much benefit.” 

This strong endorsement is seconded by many other authorities. 

The perusal of this pithy book and the use of its “ pointers ” will, in truth, 
save any company thousands of dollars. 


CLOTH, $1.50, POST-PAID. 


C. C. SHELLEY, = 


66 Park Place, New York 










iii 


THE INTERIOR CONDUIT SYSTEM. 



AS IT IS APPLIED. 


\ Standard Method of Electric Wiring. 


INTERIOR CONDUIT TUBING 

: : : and appliances. : : : 


MANUFACTURED BY 

INTERIOR CONDUIT & INSULATION CO., 

Edw'd H. Johnson, j 44 BROAD STREET, 

PRESIDENT. / NEW YORK. 


E. W. Little, 

VICE-PRESIDENT. 















































































































































IV 


The Safety Insulated Wire & Cable Co. 

OFFICE: 234 W. 29th STREET, NEW YORK, 


_ _ _ MANUFACTURERS OF - . . 

SAFETY UNDERGROUND CABLES, 

REQUA WHITE CORE INSULATION, 

SAFETY SOLID RUBBER INSULATION, 
SAFETY NAVAL MARINE INSULATION. 


ALL MADE WITH A VIEW TO 

PERFECT SAFETY FOR ELECTRIC LIGHTING. 


Insulated Wires and Cables for Electric Power, Telegraph, 
Telephone, Submarine and Inside Purposes. 

The White Core and Solid Rubber is covered with an abso¬ 
lutely Fireproof Braid, which has been approved by the Under¬ 
writers of New York, Boston, Baltimore and other large cities; 
and has been used in the new main offices of the Western Union, 
Mail and Express, and Postal Buildings; Madison Square 
Garden; Hotels Savoy, Waldorf, Holland and Netherlands; 
Presbyterian Hospital, and many more of our largest buildings. 

FIVE MILLION FEET OF SAFETY CONDUCTORS 
: : : USED AT THE WORLD’S FAIR. : : : 


OUR SAFETY NAVAL CORE has been used in the in¬ 
stallation of the following new war vessels :—NEW YORK, 
CINCINNATI, TEXAS, RALEIGH, BANCROFT, MARBLE¬ 
HEAD, COLUMBIA, MIANTONOMOH, OLYMPIA and 
OREGON. 

OVER FIVE HUNDRED MILES OF SAFETY UNDER¬ 
GROUND CABLES now in use in the New York subways. 

ARCHITECTS, PLEASE NOTE 


AND SEND FOR SAMPLES. 











































































































































